U.S. patent number 5,580,475 [Application Number 08/271,939] was granted by the patent office on 1996-12-03 for flux-cored wire for gas shield arc welding with low fume.
This patent grant is currently assigned to Kabushiki Kaisha Kobe Seiko Sho. Invention is credited to Isao Aida, Tetsuya Hashimoto, Koichi Hosoi, Kazuo Ikemoto, Tsuyoshi Kurokawa, Shigeo Nagaoka, Yoshiya Sakai.
United States Patent |
5,580,475 |
Sakai , et al. |
December 3, 1996 |
Flux-cored wire for gas shield arc welding with low fume
Abstract
Disclosed is a flux-cored wire for gas shield arc welding
comprising a mild steel sheath and a flux composition filled in the
mild steel sheath, wherein the mild steel sheath is made of a mild
steel containing, based on the total weight of the sheath, 0.02% or
less of C, 0.01 to 0.20% of Ti, and 0.01 to 0.15% of Al, the
contents of Ti and C satisfying a relation of (Ti/C.gtoreq.1.0) and
the contents of Al and C satisfying a relation of
(Al/C.gtoreq.1.5); and the flux composition contains, based on the
weight of the total wire, 0.50 to 3.60% of Mn (including the Mn
amount in the sheath), and 0.10 to 1.80% of Si (including the Si
amount in the sheath).
Inventors: |
Sakai; Yoshiya (Fujisawa,
JP), Aida; Isao (Fujisawa, JP), Ikemoto;
Kazuo (Ibaraki, JP), Kurokawa; Tsuyoshi
(Fujisawa, JP), Nagaoka; Shigeo (Fujisawa,
JP), Hashimoto; Tetsuya (Fujisawa, JP),
Hosoi; Koichi (Fujisawa, JP) |
Assignee: |
Kabushiki Kaisha Kobe Seiko Sho
(Kobe, JP)
|
Family
ID: |
26427215 |
Appl.
No.: |
08/271,939 |
Filed: |
July 8, 1994 |
Foreign Application Priority Data
|
|
|
|
|
Aug 12, 1993 [JP] |
|
|
5-220665 |
Mar 31, 1994 [JP] |
|
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6-086052 |
|
Current U.S.
Class: |
219/145.22;
219/146.22 |
Current CPC
Class: |
B23K
35/0266 (20130101); B23K 35/3608 (20130101); B23K
35/368 (20130101); B23K 35/3053 (20130101) |
Current International
Class: |
B23K
35/368 (20060101); B23K 35/36 (20060101); B23K
35/02 (20060101); B23K 35/30 (20060101); B23K
035/22 () |
Field of
Search: |
;219/145.22,146.22,146.24,146.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
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1045013 |
|
Nov 1958 |
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DE |
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2136021 |
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Sep 1984 |
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GB |
|
Other References
Database WPI, Derwent Publications Ltd., AN 81-67195D, JP-A-56
095495, Aug. 1, 1981. .
Database WPI, Derwent Publications Ltd., AN 73-61124U, SU-A-369
996, 1973. .
Patent Abstracts of Japan, vol. 9, No. 282 (M-428) (2005), Nov. 9,
1985, JP-A-60 124493, Jul. 3, 1985..
|
Primary Examiner: Shaw; Clifford C.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. A flux-cored wire for gas shield arc welding comprising a mild
steel sheath and a flux composition filled in said mild steel
sheath,
wherein said mild steel sheath is made of a mild steel containing,
based on the total weight of said sheath, 0.02% or less of C, 0.01
to 0.20% of Ti, and 0.01 to 0.15% of Al, the contents of Ti and C
satisfying a relation of Ti/C.gtoreq.1.0 and the contents of Al and
C satisfying a relation of Al/C.gtoreq.1.5; and
said flux composition contains, based on the weight of the total
wire, 0.50 to 3.60% of Mn, including the Mn amount in the sheath,
and 0.10 to 1.80% of Si, including the Si amount in the sheath.
2. A flux-cored wire for gas shield arc welding according to claim
1,
wherein said mild steel sheath is made of a mold steel containing,
based on the total weight of said sheath, 0.01% or less of C, 0.01
to 0.10% of Ti, and 0.01 to 0.05% of Al, the contents of Ti and C
satisfying a relation of Ti/C.gtoreq.3.0 and the contents of Al and
C satisfying a relation of Al/C.gtoreq.2.0.
3. A flux-cored wire for gas shield arc welding according to claim
2, wherein said flux composition contains, based on the total
weight of said wire, 0.0005 to 0.3%, as Cs or Rb converted value or
both, of the total of one or more compounds of Cs, Rb or both.
4. A metal based flux-cored wire for gas shield arc welding
according to claim 2,
wherein said flux composition comprises a metal based flux
composition containing, based on the total weight of said wire, 0.3
to 1.0% of Ti or Ti oxide, as Ti converted value, 0.1 to 0.15% of
one or more kinds of oxides or fluorides of alkali metals as alkali
metal converted value, 5 to 28% of Fe powder, and 94% or more,
based on the total weight of the flux, of a metal powder; and
further, 0.50 to 3.60% of Mn, including the Mn amount in the
sheath, and 0.10 to 1.80% of Si, including the Si amount in the
sheath.
5. A metal based flux-cored wire for gas shield arc welding
according to claim 4, wherein said flux composition contains, based
on the total weight of said wire, 1.0% or less of Al or Al.sub.2
O.sub.3, as Al converted value.
6. A metal based flux-cored wire for gas shield arc welding
according to claim 5, wherein said flux composition further
contains, based on the total weight of said wire, 0.07% or less of
C; and the contents of Ti and C in said flux satisfy a relation of
Ti/C.gtoreq.1.0.
7. A metal based flux-cored wire for gas shield arc welding
according to claim 6, wherein the contents of Ti and C satisfy the
relation of Ti/C.gtoreq.3.0.
8. A metal based flux-cored wire for gas shield arc welding
according to claim 4, wherein said flux composition further
contains, based on the total weight of said wire, 0.07% or less of
C; and the contents of Ti and C in said flux satisfy a relation of
Ti/C.gtoreq.1.0.
9. A metal based flux-cored wire for gas shield arc welding
according to claim 8, wherein the contents of Ti and C satisfy the
relation of Ti/C.gtoreq.3.0.
10. A titania based flux-cored wire for gas shield arc welding
according to claim 2,
wherein said flux composition comprises a titania based flux
composition containing, based on the total weight of said wire,
1.00 to 8.50% of TiO.sub.2, and 0.01 to 1.50% of oxides of alkali
metals as alkali metal converted value, and further 0.50 to 3.60%
of Mn, including the Mn amount in the sheath, and 0.10 to 1.50% of
Si, including the Si amount in the sheath.
11. A titania based flux-cored wire for gas shield arc welding
according to claim 10, wherein said flux composition contains,
based on the total weight of said wire, 0.01 to 1.00% of Mg, MgO or
both, as Mg converted value.
12. A titania based flux-cored wire for gas shield arc welding
according to claim 11 wherein said flux composition further
contains, based on the total weight of said wire, 0.06% or less of
C.
13. A titania based flux-cored wire for gas shield arc welding
according to claim 10, wherein said flux composition further
contains, based on the total weight of said wire, 0.06% or less of
C.
14. A metal based flux-cored wire for gas shield arc welding
according to claim 1,
wherein said flux composition comprises a metal based flux
composition containing, based on the total weight of said wire, 0.3
to 1.0% of Ti or Ti oxide, as Ti converted value, 0.1 to 0.15% of
one or more kinds of oxides or fluorides of alkali metals as alkali
metal converted value, 5 to 28% of Fe powder, and 94% or more,
based on the total weight of the flux, of a metal powder; and
further, 0.50 to 3.60% of Mn, including the Mn amount in the
sheath, and 0.10 to 1.80% of Si, including the Si amount in the
sheath.
15. A metal based flux-cored wire for gas shield arc welding
according to claim 14, wherein said flux composition contains,
based on the total weight of said wire, 1.0% or less of Al or
Al.sub.2 O.sub.3, as Al converted value.
16. A metal based flux-cored wire for gas shield arc welding
according to claim 15, wherein said flux composition further
contains, based on the total weight of said wire, 0.07% or less of
C; and the contents of Ti and C in said flux satisfy a relation of
Ti/C.gtoreq.1.0.
17. A metal based flux-cored wire for gas shield arc welding
according to claim 16, wherein the contents of Ti and C satisfy the
relation of Ti/C.gtoreq.3.0.
18. A metal based flux-cored wire for gas shield arc welding
according to claim 14, wherein said flux composition further
contains, based on the total weight of said wire, 0.07% or less of
C; and the contents of Ti and C in said flux satisfy a relation of
Ti/C.gtoreq.1.0.
19. A metal based flux-cored wire for gas shield arc welding
according to claim 18 wherein the contents of Ti and C satisfy the
relation of Ti/C.gtoreq.3.0.
20. A titania based flux-cored wire for gas shield arc welding
according to claim 1,
wherein said flux composition comprises a titania based flux
composition containing, based on the total weight of said wire,
1.00 to 8.50% of TiO.sub.2, and 0.01 to 1.50% of oxides of alkali
metals as alkali metal converted value, and further 0.50 to 3.60%
of Mn, including the Mn amount in the sheath, and 0.10 to 1.50% of
Si, including the Si amount in the sheath.
21. A titania based flux-cored wire for gas shield arc welding
according to claim 20, wherein said flux composition contains,
based on the total weight of said wire, 0.01 to 1.00% of Mg, MgO or
both, as Mg converted value.
22. A titania based flux-cored wire for gas shield arc welding
according to claim 20, wherein said flux composition further
contains, based on the total weight of said wire, 0.06% or less of
C.
23. A titania based flux-cored wire for gas shield arc welding
according to claim 21, wherein said flux composition further
contains, based on the total weight of said wire, 0.06% or less of
C.
24. A flux-cored wire for gas shield arc welding according to claim
1, wherein said flux composition contains, based on the total
weight of said wire, 0.0005 to 0.3%, as Cs or Rb converted value or
both, of the total of one or more compounds of Cs, Rb or both.
25. A metal based flux-cored wire for gas shield arc welding
comprising a mild steel sheath and a flux composition filled in
said mild steel sheath,
wherein said flux composition is filled in said mild steel sheath
in an amount of 10 to 30% based on the total weight of said wire;
and
said flux composition contains, based on the total weight of said
flux, 60 to 85% of Fe powder, 0.5% or less of C, 0.5 to 3.0% of Ti,
and 0.01 to 0.3%, as Cs or Rb converted value or both, of the total
of one or more compounds of Cs, Rb or both, the contents of C, Cs,
Rb and Ti satisfying a relation of C/(Cs+Rb)+Ti=3 or more, wherein
the values of Cs, Rb or both are converted from those in compounds
of Cs and Rb wherein percentage is based on the weight of the total
flux.
26. A metal based flux-cored wire for gas shield arc welding
according to claim 25, wherein said mild steel sheath is made of a
mild steel containing 0.01% or less of C and 0.01 to 0.20% of
Ti.
27. A flux-cored wire for gas shield arc welding according to claim
25,
wherein said mild steel sheath is made of a mild steel containing,
based on the total weight of said sheath, 0.01% or less of C, 0.01
to 0.10% of Ti, and 0.01 to 0.05% of Al, the contents of Ti and C
satisfying a relation of Ti/C.gtoreq.3.0 and the contents of Al and
C satisfying a relation of Al/C.gtoreq.2.0.
28. A titania based flux-cored wire for gas shield arc welding
comprising a mild steel sheath and a flux composition filled in
said mild steel sheath,
wherein said flux composition is filled in said mild steel sheath
in an amount of 5 to 30% based on the total weight of said wire;
and
said flux composition contains, based on the total weight of said
flux, 8 to 60% of TiO.sub.2, 0.01 to 1.0% of Cs compound as Cs
converted value, and 0.5% or less of C, said ratio between
TiO.sub.2 /compounds of Cs being in the range of from 20 to
2000.
29. A titania based flux-cored wire for gas shield arc welding
according to claim 28 wherein said mild sheath is made of a mild
steel containing, based on the total weight of said sheath, 0.02%
or less of C and 0.20% or less of Ti.
30. A flux-cored wire for gas shield arc welding according to claim
28,
wherein said mild steel sheath is made of a mild steel containing,
based on the total weight of said sheath, 0.01% or less of C, 0.01
to 0.10% of Ti, and 0.01 to 0.05% of Al, the contents of Ti and C
satisfying a relation of Ti/C.gtoreq.3.0 and the contents of Al and
C satisfying a relation of Al/C.gtoreq.2.0.
31. A metal based flux-cored wire for gas shield arc welding
comprising a mild steel sheath and a flux composition filled in
said mild steel sheath,
wherein said mild steel sheath is made of a mild steel containing,
based on the total weight of said sheath, 0.02% or less of C, 0.01
to 0.20% of Ti, and 0.01 to 0.10% of Al, the contents of Ti and C
satisfying a relation of Ti/C.gtoreq.1.0 and the contents of Al and
C satisfying a relation of Al/C.gtoreq.1.5; and
said flux composition contains, based on the total weight of said
wire, 0.01 to 0.30%, as alkali metal converted value, of one or
more kinds of oxides and fluorides of alkali metals other than Cs
and Rb, 5 to 28% of Fe powder, 94% or more, based on the total
weight of said flux, of metal powder, and 0.001 to 0.10%, as Cs or
Rb converted value or both, of the total of one or more compounds
of Cs, Rb or both, and further 0.50 to 3.60% of Mn, including the
Mn amount in the sheath, and 0.10 to 1.80% of Si, including the Si
content in the sheath.
32. A titania based flux-cored wire for gas shield arc welding
comprising a mild steel sheath and a flux composition filled in
said mild steel sheath,
wherein said mild steel sheath is made of a mild steel containing,
based on the total weight of said sheath, 0.02% or less of C, 0.01
to 0.20% of Ti, and 0.01 to 0.15% of Al, the contents of Ti and C
satisfying a relation of Ti/C.gtoreq.1.0 and the contents of Al and
C satisfying a relation of Al/C.gtoreq.1.5; and
said flux composition contains, based on the total weight of said
wire, 1.00 to 8.50% of TiO.sub.2, 0.01 to 1.50%, as alkali metal
converted value, of oxides of alkali metals other than Cs, 0.0005
to 0.3%, as Cs converted value, of a compound of Cs, said ratio
between TiO.sub.2 /compounds of Cs, as Cs converted value being in
the range of from 20 to 2000, 0.06% or less of C, 0.50 to 3.60% of
Mn, including the Mn amount in the sheath, and 0.10 to 1.50% of Si,
including the Si amount in the sheath.
33. A titania based flux-cored wire for gas shield arc welding
according to claim 32, wherein said flux composition contains,
based on the total weight of said wire, 0.01 to 1.00% of Mg, MgO or
both, as Mg converted value.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flux-cored wire for gas shield
arc welding, and particularly to a flux-cored wire for gas shield
arc welding capable of reducing the amount of fume generation,
which is suitable for welding of mild steel, high tensile strength
steel, low alloy steel and the like.
2. Description of the Related Art
Recently, there has been a problem in lack of man power in the
whole industrial field. In particular, the industries of
steel-frame work, machine-making, and shipbuilding have been
seriously short of welders, and have developed techniques for
enhancement of efficiency, automation and robotic process for
welding, and also have made efforts to improve the hard, dirty and
dangerous welding work environments.
Because of lack of welders, flux-cored wires for gas shield arc
welding have increasingly required in terms of (1) easy welding,
and (2) high efficiency welding. In particular, metal based
flux-cored wires have a feature of lowering the amount of slag
generation in addition to the above advantages (1) and (2), and are
expected to be more widely used. However, the wires of this kind
have a disadvantage in making the welding work environments poor
resulting from generation of a large amount of welding fume.
Techniques of reducing welding fume have been disclosed, for
example in Japanese Patent Publication Nos. 1403569, 1572313 and
1572327. In particular, it is well known that the reduction of the
contents of carbon and oxygen in a sheath is effective to reduce
welding fume. However, metal based flux-cored wires are used with a
high current (for example, 300 to 500 A) to obtain a high
deposition rate, to thus exponentially increase the amount of
welding fume generation. This drawback cannot be solved by the
conventional techniques.
On the other hand, titania based flux-cored wires have a feature
being low in the amount of spatter generation and excellent in bead
appearance, and further being easily used for welding in all
positions, so that they have been widely used in the industries of
shipbuilding, bridge construction, and machine-making. However, on
the other hand, the lack of welders has become severe because of
the harsh welding environments at high temperatures and with a
large amount of welding fume.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a flux-cored wire
for gas shield arc welding which is capable of reducing the amount
of fume generation.
Another object of the present invention is to provide a flux-cored
wire for gas shield arc welding wherein the generation amount of
fume can be reduced by improvement in a sheath composition.
A further object of the present invention is to provide a
flux-cored wire for gas shield arc welding wherein the generation
amount of fume can be reduced by improvement in compositions of a
sheath and a flux.
A specific object of the present invention is to provide a metal
based flux-cored wire for gas shield arc welding wherein the
generation amount of fume can be reduced by improvement in a flux
composition.
Another specific object of the present invention is to provide a
metal based flux-cored wire for gas shield arc welding wherein the
generation amount of fume can be reduced by improvement in
compositions of a sheath and a flux.
A further specific object of the present invention is to provide a
titania based flux-cored wire for gas shield arc welding wherein
the amount of fume generation can be reduced by improvement in a
flux composition.
Still a further specific object of the present invention is to
provide a titania based flux-cored wire for gas shield arc welding
wherein the amount of fume generation can be reduced by improvement
in compositions of a sheath and a flux.
To reduce the amount of fume generation in a flux-cored wire for
gas shield arc welding, the present inventors have examined the
sheath composition, and found that the adjustment of contents of Ti
and Al in a sheath is particularly effective in addition to the
conventional technique of reducing the C content in the mild steel
sheath; and at the same time, contents of Mn and Si in the flux are
required to be adjusted for deoxidation, enhancement of strength
and toughness of weld, and improvement of bead shape.
On the basis of this knowledge, according to the present invention,
there is provided a flux-cored wire for gas shield arc welding
including a mild steel sheath and a flux composition filled in the
mild steel sheath,
wherein the mild steel sheath contains, based on the weight of the
total sheath, 0.02% or less of C, 0.01 to 0.20% of Ti, and 0.01 to
0.15% of Al, the contents of Ti and C satisfying a relation of
(Ti/C.gtoreq.1.0) and the contents of Al and C satisfying a
relation of (Al/C.gtoreq.1.5); and
the flux composition contains, based on the weight of the total
wire, 0.50 to 3.60% of Mn (including the Mn amount in the sheath),
and 0.10 to 1.80% of Si (including the Si amount in the
sheath).
On the other hand, to reduce the amount of fume generation in a
flux-cored wire for gas shield arc welding, the present inventors
have examined a method of reducing fume in terms of the flux
composition, and found that in either of a metal based flux or a
titania based flux, the amount of fume generation can be reduced by
suitably adding one or two kinds of Cs and Rb in the flux.
On the basis of this knowledge, according to the present invention,
there is provided a metal based flux-cored wire for gas shield arc
welding including a mild steel sheath and a flux composition filled
in the mild steel sheath,
wherein the flux composition is filled in the mild steel sheath in
an amount of 10 to 30% (based on the weight of the total wire);
and
the flux composition contains, based on the weight of the total
flux, 60 to 85% of Fe powder, 0.5% or less of C, 0.5 to 3.0% of Ti,
and 0.01 to 0.3% (Cs and/or Rb converted value) of the total of one
or two kinds of compounds of Cs and/or Rb, the contents of C, Cs,
Rb and Ti satisfying a relation of {C/(Cs+Rb)}+Ti=3 or more (the
contents of Cs and/or Rb are converted from those in the compounds
of Cs and/or Rb (% based on the weight of the total flux)).
Moreover, according to the present invention, there is provided a
titania based flux-cored wire for gas shield arc welding including
a mild steel sheath and a flux composition filled in the mild steel
sheath,
wherein the flux composition is filled in the mild steel sheath in
an amount of 5 to 30% (based on the weight of the total wire);
and
the flux composition contains, based on the weight of the total
flux, 8 to 60% of TiO.sub.2, 0.01 to 1.0% of Cs compounds (Cs
converted value) and 0.5% or less of C, the ratio between the
TiO.sub.2 /compounds of Cs (Cs converted value) being in the range
of from 20 to 2000.
Additionally, the present inventors have found that the amount of
fume generation can be extremely reduced by the addition of one or
two kinds of Cs and Rb in a metal based or titania based flux, in
combination with the reduction in the C content and the adjustment
of the contents of Ti and Al in the mild steel sheath described
above.
On the basis of this knowledge, according to the present invention,
there is provided a metal based flux-cored wire for gas shield arc
welding including a mild steel sheath and a flux composition filled
in the mild steel sheath,
wherein the mild steel sheath contains, based on the total weight
of the sheath, 0.02% or less of C, 0.01 to 0.20% of Ti, and 0.01 to
0.10% of Al, the contents of Ti and C satisfying a relation of
(Ti/C.gtoreq.1.0) and the contents of Al and C satisfying a
relation of (Al/C.gtoreq.1.5); and
the flux composition contains, based on the weight of the total
wire, 0.01 to 0.30% (alkali metal converted value) of one or more
kinds of oxides and fluorides of alkali metals excluding Cs and Rb,
5 to 28% of Fe powder, 94% or more (based on the weight of the
total flux) of metal powder, and 0.001 to 0.10% of the total of one
or two kinds of Cs and Rb, and further 0.50 to 3.60% of Mn
(including the Mn amount in the sheath) and 0.10 to 1.80% of Si
(including the Si content in the sheath).
Moreover, according to the present invention, there is provided a
titania based flux-cored wire for gas shield arc welding including
a mild steel sheath and a flux composition filled in the mild steel
sheath,
wherein the mild steel sheath contains, based on the weight of the
total sheath, 0.02% or less of C, 0.01 to 0.20% of Ti, and 0.01 to
0.15% of Al, the contents of Ti and C satisfying a relation of
(Ti/C.gtoreq.1.0) and the contents of Al and C satisfying a
relation of (Al.gtoreq.1.5); and
the flux composition contains, based on the weight of the total
wire, 1.00 to 8.50% of TiO.sub.2, 0.01 to 1.50% (alkali metal
converted value) of oxides of alkali metals excluding Cs, 0.0005 to
0.3% (Cs converted value) of compounds of Cs, the ratio between
TiO.sub.2 /compounds of Cs (Cs converted value) being in the range
of from 20 to 2000, and 0.06% or less of C, and further 0.50 to
3.60% of Mn (including the Mn amount in the sheath) and 0.10 to
1.50% of Si (including the Si amount in the sheath).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing a relationship between the amount of fume
generation and the contents of C, Ti and Al in a mild steel
sheath;
FIG. 2 is a graph showing a relationship between the amount of fume
generation and the contents of Ti, C and Al in a mild steel
sheath;
FIG. 3 shows an apparatus provided with a fume collecting box;
FIG. 4 is a graph showing a relationship between the amount of fume
generation and the C content in a metal based flux;
FIG. 5 is a graph showing a relationship between the amount of fume
generation and the Ti content in a metal based flux;
FIG. 6 is a graph showing a relationship between the amount of fume
generation and the contents of Cs and Rb in a metal based flux;
FIG. 7 is a graph showing a relationship between the amount of fume
generation and the C content in a titania based flux;
FIG. 8 is a graph showing a relationship between the amount of fume
generation and the Cs content in a titania based flux;
FIG. 9 is a graph showing a relationship between the amount of fume
generation and the TiO.sub.2 /Cs ratio in a titania based flux;
FIG. 10 is a view showing an example of the sectional shape of a
flux-cored wire;
FIG. 11 is a graph showing a relationship between the amount of
fume generation and the C content in a mild steel sheath of a metal
based flux-cored wire;
FIG. 12 is a graph showing a relationship between the amount of
fume generation and the Ti content in a mild steel sheath of a
metal based flux-cored wire; and
FIG. 13 is a graph showing a relationship between the amount of
fume generation and the contents of Cs and Rb in a flux of a metal
based flux-cored wire.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(1) Reduction of fume mainly by adjustment of sheath
composition
The reduction of fume mainly by adjustment of a mild steel sheath
composition according to the present invention will be described in
detail.
First, various experiments have been made to reduce welding fume in
terms of the sheath composition, which gave the results shown as
follows.
In these experiments, flux-cored wires (diameter: 1.4 mm) were
fabricated using a metal based flux composition (flux ratio: 15%)
shown by No. 1 in Table 2 described later in combination with mild
steel sheaths (C: 0.003-0.03%, Mn: 0.20-0.30%, Si: 0.01-0.03%, P:
0.008-0.011%, S: 0.005-0.007%, N: 0.002-0.004%, and Ti and Al:
variable).
The wires thus obtained were used for performing a downward bead-on
plate welding test using a test plate (JIS G3106 SM490A, thickness:
12 mm) under the following welding conditions. The amount of
welding fume generated in the above test was measured according to
JIS Z3930, using a fume collecting box shown in FIG. 3.
(Welding Conditions)
Welding current: 350 A
Welding voltage: 36 V
Welding rate: 30 cm/min
Wire extension: 25 mm
Polarity: DCEP (wire: plus)
Shield gas: CO.sub.2 (flow rate: 25 l/min)
FIGS. 1 and 2 show relationships between the amount of welding fume
generation and the contents of Ti, Al and C in a mild steel sheath,
which are obtained on the basis of the above experiments. As will
be apparent from FIGS. 1 and 2, the complex addition of Ti and Al
in respective amounts of 0.01% or more in the mild steel sheath is
effective to reduce the amount of fume generation, in addition to
the reduction of the C content according to the conventional
technique. Moreover, the single addition of Al is not effective;
but the complex addition of Al and Ti is significantly effective.
Additionally, to effectively reduce the amount of welding fume
generation, the contents of Ti and Al are specified to be under the
conditions that C.ltoreq.0.02%, Ti/C.gtoreq.1.0%,
Al/C.gtoreq.1.5%.
The reason why the addition of Ti and Al is effective to reduce the
amount of welding fume generation is that Ti and Al have high
affinity with oxygen and generate oxides having high solidifying
points, to form an oxide film on the surface of hanging droplet at
the tip of a wire during arc welding, thus suppressing the
explosive generation of CO and CO.sub.2, which are regarded as the
source of fume generation, caused by the reaction between oxygen
and carbon.
Moreover, it was revealed that the upper limits of Ti and Al must
be in a relation of (Ti.ltoreq.0.20% and Al.ltoreq.0.15%) for
avoiding the material deterioration such as reduction in ductility
and hardening which are caused by their high yields in weld.
For this reason, a mild steel sheath suitable for reduction in
welding fume contains, based on the total weight of the sheath,
0.02% or less of C, 0.01 to 0.20% of Ti, and 0.01 to 0.15% of Al,
the contents of Ti and C satisfying a relation of (Ti/C.gtoreq.1.0)
and the contents of Al and C satisfying a relation of
(Al.gtoreq.1.5).
Preferably, the above mild steel sheath contains 0.01% or less of
C, 0.01 to 0.10% of Ti, and 0.01 to 0.05% of Al, the contents of Ti
and C satisfying a relation of (Ti/C.gtoreq.3.0) and the contents
of Al and C satisfying a relation of (Al/C.gtoreq.2.0).
In addition, under the consideration of the workability in the
rolling and/or drawing processes for wire fabrication, preferably,
the content of Mn is in the range of from 0.10 to 0.70% and the
content of Si is in the range of 0.35% or less.
A flux composition filled in the above mild steel sheath may be
constituted of any type of composition so long as the Mn content
(including the Mn content in the sheath) is in the range of from
0.50 to 3.60%, and the Si content is in the range of from 0.10 to
1.80%.
Here, Mn is added in the flux under the consideration of the Mn
content in the mild steel sheath, to act as a deoxidizing agent, to
improve toughness by enhancement of strength and hardenability, and
to improve bead shape (especially, for horizontal fillet welding)
due to an increase in viscosity of molten metal slag. In this case,
when the Mn content is less than 0.5%, it is difficult to obtain
the sufficient strength for a mild steel and to obtain a good bead
shape. Meanwhile, over 3.6%, the strength of weld is excessively
increased, tending to cause low temperature cracking. Accordingly,
the Mn content is specified to be in the range of from 0.50 to
3.6%. The sources of Mn include Mn, Fe-Mn, Fe-Si-Mn and the
like.
Si has the same effect as that of Mn. When the Si content is less
than 0.1%, the effects to act as a deoxidizing agent, to improve
toughness, and to improve bead shape cannot be obtained. Meanwhile,
when being more than 1.8%, the yield of Si in weld is excessively
increased, to rather lower toughness and ductility. Accordingly,
the Si content is specified to be in the range of from 0.10 to
1.8%. The sources of Si include Si, Fe-Si, Fe-Si-Mn, Fe-Si-Mg and
the like.
More preferably, the flux composition contains, based on the weight
of the total wire, 0.005 to 0.3% (Cs and/or Rb converted value) of
one or two kinds of compounds of Cs and/or Rb, in addition to the
above Mn and Si.
For example, preferably, a metal based flux composition contains,
based on the weight of the total wire, 0.03 to 1.0% of Ti or Ti
oxide (Ti converted value), 0.01 to 0.15% of one or more kinds of
oxides or fluorides of alkali metals (alkali metal converted
value), 5 to 28% of Fe powder, and 94% or more (based on the weight
of the total flux) of a metal powder, and further, 0.50 to 3.60% of
Mn (including the Mn amount in the sheath) and 0.10 to 1.80% of Si
(including the Si amount in the sheath).
More preferably, the above flux composition contains, based on the
weight of the total wire, 1.0% or less of Al or Al.sub.2 O.sub.3
(Al converted value).
Moreover, the flux composition preferably contains, based on the
weight of the total wire, 0.07% or less of C wherein the contents
of Ti and C satisfy a relation of Ti/C.gtoreq.1.0).
Additionally, in the above flux composition, the contents of Ti and
C preferably satisfy a relation of Ti/C.gtoreq.3.0).
In the above metal based flux, Ti is effective to reduce welding
fume, to improve penetration shape, and to improve arc stability,
and is added in a flux under the consideration of the Ti content in
a mild steel sheath. Namely, the Ti content in an amount of 0.03%
or more is effective to reduce welding fume, and to improve
penetration depth and arc stability. However, when being more than
1.0%, Ti in the form of metal or alloy is greatly transferred in
weld, to extremely reduce ductility; and Ti oxide excessively
generates slag, tending to cause slag inclusion upon continuous
multi-layer welding.
Alkali metals such as Li, Na, K, Rb and Cs are added to lower arc
stability and to reduce spatter generation. Alkali metals have high
hygroscopicity; accordingly, they are desirable to be added by one
or more kinds in the form of oxides or fluorides. The reason why
the contents of alkali metals are specified in the above range is
as follows. When the contents of alkali metals are less than 0.01%,
the effects to improve arc stability and to reduce the amount of
spatter generation cannot be obtained. Meanwhile, over 0.15%, the
amount of spatter generation is rather increased and the effect of
reducing welding fume by the addition of Ti and Al cannot be
obtained, because alkali metals are high in vapor pressure.
In addition, feldspar, sodium silicate anhydride, water glass,
complex oxides of Li, Na, K and the like, cryolite, fluorides such
as potassium silicofluoride, sodium silicofluoride, and carbonates
of alkali metals in small amounts are similarly effective because
they are dissolved by welding arc into oxides.
Fe powder is added according to a flux ratio to obtain a high
deposition rate. When the flux ratio (% based on the weight of the
total wire) is less than 10%, spatter of large grain is increased
because the wall thickness of the sheath is excessively thick.
Meanwhile, over 30%, the wire is softened along with the reduction
in the wall thickness of the sheath, with a result of the reduction
of feedability, and further arc is significantly expanded, tending
to reduce penetration depth and to generate undercut. Accordingly,
the flux ratio is preferably in the range of from 10 to 30%.
Fe powder is added according to the above flux ratio; however, less
than 5%, it is difficult to obtain a high deposition rate which is
regarded as the feature of the metal based flux-cored wire.
Meanwhile, over 28%, the other components such as a deoxidizing
agent are insufficient, which makes it difficult to secure the
specified mechanical properties of weld and prevent weld defects
such as pit and blowhole. Accordingly, Fe powder is specified to be
in the range of from 5 to 28%.
To secure a high deposition rate as the feature of the metal based
flux-cored wire, and to secure a slag amount sufficient for
continuous multi-layer welding, the metal powder ratio in the flux
excluding non-metals such as oxides, fluorides and carbonates must
be in the range of 94% or more.
Al is effective to reduce the generation amount of welding fume,
although being smaller in its effect than Ti, and is added if
needed. In this case, over 1.0%, the addition of Al in the form of
metal or alloy excessively increases the yield of Ti into weld,
significantly reducing ductility; and the addition of Al in the
form of Al.sub.2 O.sub.3 significantly reduces slag removability.
The sources of Al include Al, Al alloys such as Fe-Al and Al-Li,
and oxides such as Al.sub.2 O.sub.3.
C may be suitably added in the flux under consideration of the C
content in the mild steel sheath if needed, to act as a deoxidizing
agent, to secure strength and toughness by improvement of
hardenability, and to obtain penetration depth. In the case, when
the C content is more than 0.07%, the effect of reducing the amount
of fume generation by the addition of Ti and Al cannot be obtained,
to significantly increase the amount of welding fume generation.
Accordingly, the C content is in the range of 0.07% or less. The
sources of C include Fe-Mn, Fe-Si-Mn, graphite, Fe powder (carbon
steel, cast iron) and carbonate.
To reduce the amount of welding fume generation in terms of the
flux composition, it is effective to reduce the C content in the
flux and simultaneously add Ti according to the C content. Namely,
the Ti/C ratio adjusted to be 1.0 or more gives the significant
effect to reduce welding fume. In addition, the sources of Ti
includes metal Ti, alloys such as Fe-Ti, rutile, reduced ilmenite,
leucoxene, ilmenite, and oxides such as potassium titanate.
Moreover, within the range of satisfying the above ratio of metal
powder, oxides such as SiO.sub.2, ZrO.sub.2, CaO and FeO may be
added to further improve bead appearance/shape; and bismuth oxide
(Bi.sub.2 O.sub.3) specified to be in an amount of 0.1% or less
(based on the weight of the total wire) not to generate high
temperature cracking may be added to improve slag removability, and
MgO or Mg in an amount of 0.2% (based on the weight of the total
wire) not to deteriorate bead shape may be added to improve slag
removability.
Next, a titania based flux composition preferably contains, based
on the weight of the total wire, 1.00 to 8.50% of TiO.sub.2, and
0.01 to 1.50% of oxides of alkali metals (alkali metal converted
value); and further 0.50 to 3.60% of Mn (including the Mn amount in
the sheath) and 0.10 to 1.50% of Si (including the Si amount in the
sheath).
More preferably, the above flux composition contains, based on the
weight of the total wire, 0.01 to 1.00% of Mg and/or MgO (Mg
converted value).
Alternatively, the above flux composition contains, based on the
weight of the total wire, 0.06% or less of C.
In the above titania based flux, TiO.sub.2 is expected to act as a
slag removing agent or an arc stabilizer. The TiO.sub.2 content is
required to be added in an amount of at least 1.00% or more to
improve bead appearance/shape and arc stability in downward or
horizontal welding. However, when the TiO.sub.2 content is more
than 8.50%, the solidifying point of slag is made higher, and the
viscosity thereof is excessively increased, tending to generate
slag inclusion and blowhole on the surface of bead. The sources of
TiO.sub.2 include rutile, reduced ilmenite, leucoxene, ilmenite,
and oxides such as potassium titanate.
The addition of alkali metals such as Li, Na, K, Rb and Cs is
effective to enhance arc stability and to reduce the amount of
spatter; however, they act as sources of significantly generating
welding fume. In particular, fluorides and carbonate of alkali
metals and simple oxides such as Na.sub.2 O, K.sub.2 O and Li.sub.2
O become the sources of significantly generating welding fume.
However, the present inventors have found the fact that the
addition of the alkali metals such as Li, Na, K, Rb and Cs in the
form of complex oxides combined with one kind or more kinds of
Ti.sub.x O.sub.y, Al.sub.x O.sub.y, Fe.sub.x O.sub.y, Mn.sub.x
O.sub.y, Si.sub.x O.sub.y and Zr.sub.x O.sub.y (x, y: positive
number), suppresses the increase in the amount of welding fume
generation, and rather reduces the amount of fume generation in the
cases of Cs and Rb. The reason why the added amount of oxides of
alkali metals is specified in the above range is as follows. When
being less than 0.01%, the effects to improve arc stability and to
reduce the amount of spatter generation cannot be obtained.
Meanwhile, over 1.50%, the fume reducing effect by the limitation
of the sheath composition is little expected except for Rb and Cs,
and also slag removability is significantly reduced. Each of oxides
of alkali metals is added in an amount to be converted in an alkali
metal. The examples of the complex oxides includes LiFeO.sub.2,
Li.sub.2 SiO.sub.3, Li.sub.2 MnO.sub.3, Li.sub.2 ZrO.sub.3,
Li.sub.2 TiO.sub.3, Na.sub.2 SiO.sub.3, NaAlSi.sub.3 O.sub.3,
K.sub.2 TiO.sub.3, KAlSi.sub.3 O.sub.3 and CsAlSi.sub.2 O.sub.6.
These complex oxides are fabricated by a high temperature baking or
melting method, or obtained using natural materials such as
feldspar.
An Al containing sheath is used for reducing welding fume, and
compounds of alkali metals are incorporated in the flux for
improving arc stability; however, these tend to deteriorate slag
removability in the cases of narrow groove angle and of a large
welding thermal input. To improve slag removability, Mg and/or MgO
are added, if needed. The reason why the added amount of Mg and/or
MgO is specified in the above range is that, when being less than
0.01%, the effect to improve slag removability can be obtained; and
over 1.00%, the amount of welding fume generation is increased.
Moreover, Mg and MgO act to reduce oxygen in weld and are effective
to improve toughness and blowhole resistance. The sources of Mg
include metal Mg, alloys such as Al-Mg, Li-Mg, Ni-Mg, and Si-Mg;
and the sources of MgO include clinker, magnesium silicate and
olivin sand.
C is added in the flux under consideration of the C content in the
sheath, if needed, to act as a deoxidizing agent, to adjust
strength, secure toughness due to enhancement of hardenability, and
to obtain a suitable penetration depth due to acceleration of arc
concentration. In this case, when the C content is more than 0.06%,
the effect of reducing welding fume by the addition of Ti and Al in
the sheath cannot be obtained, to significantly increase the amount
of welding fume generation, and to increase the amount of spatter
generation.
In addition, under the consideration of bead appearance/shape,
usability characteristics and mechanical properties of weld, the
following components may be added in the flux and/or the sheath,
based on the weight of the total wire.
The addition of SiO.sub.2 in an amount of 0.1% or more is effective
to improve usability characteristics such as bead appearance/shape
and slag removability; however, over 1.5%, the acidity and
viscosity of slag are excessively increased, to reduce cleanliness
of weld and to easily generate slag inclusion and blowholes.
ZrO.sub.2 acts to increase the solidifying point of slag. The
addition of ZrO.sub.2 in an amount of 0.05% or more is effective to
improve bead shape in fillet welding, especially horizontal fillet
welding; however, over 0.6%, slag removability and bead appearance
are deteriorated.
Al.sub.2 O.sub.3 acts to increase the solidifying point and
viscosity of slag and hence to improve bead shape in vertical
upward welding and overhead welding. To obtain the above effect,
Al.sub.2 O.sub.3 must be added in an amount of 0.05% or more.
However, over 1.0%, the viscosity of slag is excessively increased,
to deteriorate bead appearance/shape and workability in vertical
downward welding, and to significantly cause the burning of
slag.
Al, which is added both in the sheath and flux, acts as a
deoxidizing agent and a nitrogen fixing agent, and further has the
same effect as that of Al.sub.2 O.sub.3. The addition range and the
limitation reason of Al are the same as those of Al.sub.2
O.sub.3.
Fluorides of alkali metals such as Na, K, Li and alkali earth
metals such as Ca and Sr act to reduce the amount of hydrogen of
weld. To obtain the above effect, metal fluorides must be added in
an amount of 0.01% or more; however, over 0.2%, the amount of fume
generation is significantly increased and the viscosity of molten
slag is lowered, to significantly deteriorate bead shape in upward
welding and horizontal welding.
Bismuth oxide (Bi.sub.2 O.sub.3) presents at the interface between
weld and slag, to significantly improve slag removability. To
achieve the above effect, Bi.sub.2 O.sub.3 is added in an amount of
0.005% or more; however, over 0.05%, high temperature cracking is
easily generated.
Moreover, as is well known, the addition of Ti and B having the
grain refining function in the sheath metal, other than C, Mn and
Si, is effective to improve notch toughness of weld. Similarly, the
following components are added in the metal sheath and/or flux
based on the weight of the total wire, if needed.
Ti is added in the flux in the form of TiO.sub.2 and in the metal
sheath; however, to increase the deoxidizing effect and the grain
refining effect, Ti may be further added in the flux in an amount
of 0.7% or less. When being more than 0.7%, the yield of Ti in weld
is enhanced, to excessively increase the strength of weld and
reduce the toughness thereof.
B is added together with Ti and TiO.sub.2 to refine grains of weld,
thus significantly increasing the toughness. B is added in the
metal sheath and flux (in the form of an alloy such as Fe-B or
B.sub.2 O.sub.3) in an amount of 0.002% to achieve the above
effect; however, over 0.025%, the yield of B in weld is enhanced,
to harden the weld, rather reducing toughness, and to make
sensitive the weld to high temperature cracking.
Ni is an element of strengthening the matrix of crystal structure
of weld, and improving toughness by hardening; however, over 4.0%,
it acts to significantly accelerate hardenability of weld and to
significantly reduce cracking resistance.
Moreover, the flux-cored wire may contain Ni, Cu and Cr when used
for weather resisting steel, and contain Ni, Cr and Mo when used
for heat resisting steel in the flux or the metal sheath while
being matched to the base material components.
In addition, the flux ratio (flux weight/total wire weight) in the
wire is preferably in the range of from 5 to 30%. In general, the
flux ratio is determined in combination with the wire sectional
shape in viewpoint of the uniformity in fusion of wire and
workability of wire. Namely, for a small diameter wire, a low flux
ratio and a single section are desirable; and for a large diameter
wire, a high flux ratio and a complex section are desirable.
(2) Reduction of fume mainly by adjustment of flux composition
(metal base)
Next, the reduction of fume mainly by adjustment of a metal based
flux composition according to the present invention will be
described.
First, various experiments have been made to reduce welding fume in
terms of flux composition, which gave the result shown as
follows.
In these experiments, flux-cored wires (diameter: 1.4 mm) were
fabricated using metal based flux compositions (flux ratio: 15%) in
which the contents of C, Ti, Cs and Rb were variable, in
combination with a mild steel sheath.
The wires thus obtained were used for performing a downward bead-on
plate welding test using a test plate (JIS G3106 SM490A, thickness:
12 mm) under the following welding conditions. The amount of
welding fume generated in the above test was measured according to
JIS Z3930, using a fume collecting box shown in FIG. 3.
(Welding conditions)
Welding current: 350 A
Welding voltage: suitable (arc extension: 1.5 mm from the surface
of base material)
Welding rate: 30 cm/min
Polarity: DCEP (wire: plus)
Distance between tip and base metal: 25 mm
The test results are shown in FIGS. 4, 5 and 6. As will be apparent
from these figures, 1the content of C, 2the content of Ti, and 3the
contents of Cs and/or Rb are important to reduce the amount of fume
generation of the metal based flux-cored wire.
Accordingly, it is revealed that, to reduce the amount of fume
generation of the metal based flux-cored wire, the essential
requirements lie in (1) the reduction of the C content, (2) the
increase in the Ti content, and (3) the addition of the contents of
Cs and/or Rb. If a wire does not satisfy either of the above
requirements, it cannot achieve the effect of reducing the amount
of fume generation. Namely, by satisfying all of the above three
requirements, it is possible to achieve the good effect of reducing
the generation amount of fume generation.
On the basis of the above experimental results, according to the
present invention, in a metal based flux-cored wire for achieving
the reduction of fume,
a flux composition is filled in the mild steel sheath in an amount
of 10 to 30% based on the weight of the total wire; and
the flux composition contains, based on the weight of the total
flux, 60 to 85% of Fe powder, 0.5% or less of C, 0.5 to 3.0% of Ti,
and 0.01 to 0.3% (Cs and/or Rb converted value) of the total of one
or two kinds of compounds of Cs and/or Rb, the contents of C, Cs,
Rb and Ti satisfying a relation of {C/(Cs+Rb)}+Ti=3 or more (the
contents of Cs and/or Rb are converted from those in the compounds
of Cs and/or Rb (% based on the weight of the total flux).
Here, when the content of Fe powder is less than 60%, the
efficiency, which is a feature of the metal based flux-cored wire,
is reduced; however, over 85%, the other components (deoxidizing
agent, etc.) are insufficient, tending to generate weld defects
such as pit and blowhole, which makes it difficult to secure good
weld.
When the C content is more than 0.5%, the amount of welding fume
generation is increased (see FIG. 4), and the amount of spatter
generation is also increased. Accordingly, the C content is limited
to be 0.5% or less.
When the Ti content is less than 0.5%, the effect of reducing the
amount of fume generation cannot be obtained (see FIG. 5); however,
over 3.0%, the amount of slag generation is increased, which is
undesirable in terms of toughness and cracking resistance of weld.
In addition, Ti may be added in the form of ferro-alloys and
oxides, other than Ti metal.
When the total amount of one or two or more kinds of Cs and Rb is
less than 0.01%, the effect of reducing the amount of fume
generation cannot be obtained (see FIG. 6); however, over 0.3%,
hygroscopic resistance is deteriorated, to reduce blowhole
resistance and increase the generation amount of diffusive hydrogen
of weld, thereby deteriorating cracking resistance. In addition, Cs
and Rb may be added in the suitable form, and particularly, Cs may
be added in the form of CsCO.sub.3 or complex oxides with TiO.sub.2
and SiO.sub.2.
However, the relationship between the ratio of C to (Cs+Rb) and Ti
is limited in viewpoint of weld defects. Namely, when the total
amount of [{C/(Cs+Rb)}+Ti] is less than 3, the penetration depth is
made small, tending to generate weld defects such as incomplete
penetration and incomplete fusion in groove welding. Accordingly,
the total amount of [{C/(Cs+Rb)}+Ti] must be in the range of 3 or
more. In the equation of [{C/(Cs+Rb)}+Ti], the first term is
dimensionless and the second term is expressed by %; however, the
total of the respective values is specified to be 3 or more.
When the flux ratio (% based on the weight of the total wire) is
less than 10%, spatter of large grain is increased. Meanwhile, over
30%, the wire is softened along with an decrease in the thickness
of the sheath, which reduces the feedability of the wire and tends
to generate weld defects such as undercut due to arc instability.
Accordingly, the flux ratio is in the range of from 10 to 30%.
In addition, the other components, which are commonly added in the
metal based flux-cored wire, may be of course added in this
flux.
The sheath is made of a common mild steel material, preferably, is
made of a mild steel containing 0.01 or less of C and 0.01 to 0.20%
of Ti for reducing the welding fume.
The mild steel sheath further effective to reduce welding fume is
made of a mild steel containing 0.01% or less of C, 0.01 to 0.10%
of Ti, and 0.01 to 0.05% of Al, the contents of Ti and C satisfying
a relation of (Ti/C.gtoreq.3.0) and the contents of Al and C
satisfying a relation of (Al/C.gtoreq.2.0).
(3) Reduction of fume mainly by adjustment of flux composition
(titania base)
Next, the reduction of fume mainly by adjustment of a titania based
flux composition according to the present invention will be
described.
First, various experiments have been made to reduce welding fume in
terms of flux composition, which gave the result shown as
follows.
In these experiments, flux-cored wires (1.2 mm) were fabricated
using various titania based flux compositions in combination with a
mild steel sheath. The wires thus obtained were tested under the
following welding conditions for examining the effect of reducing
welding fume according to JIS Z3930.
(Welding conditions)
Welding process: downward bead-on plate welding
Welding current: 300 A
Arc voltage: suitable voltage to obtain arc extension of 1.5 to 2.0
mm)
Welding rate: 30 cm/min
Wire extension: 25 mm
Polarity: DCEP (wire: plus)
Shield gas: 100% CO.sub.2 (flow rate: 25 l/min)
Test plate: JIS G3106 SM490A (thickness: 12 mm)
The test results are shown in FIGS. 7 and 8. As will be apparent
from these figures, to reduce the amount of fume generation of the
titania based flux-cored wire, 1the content of C, 2the content of
Cs, and 3the ratio of TiO.sub.2 /Cs are important in viewpoint of
the flux composition; and 4the content of C, and 5the content of Ti
are important in the viewpoint of the steel sheath composition. In
addition, the present inventors have found the fact that, to reduce
the fume in the titania based flux-cored wire, the addition of only
one of the flux composition and the steel sheath composition is
effective; however, the addition of the combination thereof is
further effective.
On the basis of the above experimental results, the titania based
flux-cored wire for achieving the reduction in the amount of fume
generation includes a mild steel sheath and a flux composition
filled in the mild steel sheath,
wherein the flux composition is filled in the mild steel sheath in
an amount of 5 to 30% based on the weight of the total wire;
and
the flux composition contains, based on the weight of the total
flux, 8 to 60% of TiO.sub.2, 0.01 to 1.0% of Cs compounds (Cs
converted value) and 0.5% or less of C, the ratio between TiO.sub.2
/compounds of Cs (Cs converted value) being in the range of from 20
to 2000.
C is added in the flux under the consideration of the C content in
the sheath, if needed, to be as a deoxidizing agent, to secure
strength and toughness by enhancement of hardenability, and to
improve penetration depth by acceleration of arc concentration. In
this case, the addition of C in excess of 0.5% significantly
increases the amount of fume generation and also significantly
increases the amount of spatter generation (see FIG. 7). The reason
for this is that, when the C content is more than 0.5%, CO and
CO.sub.2, which are regarded as the source of fume generation, are
explosively produced by the reaction between C and O.sub.2.
Accordingly, the C content in the flux is limited to be 0.5% or
less.
The mechanism of reducing the amount of fume generation by the
addition of Cs is unclear; however, one reason for this is due to
the fact that Cs reduces the potential gradient of arc, to enhance
the arc stability. The effect of reducing the amount of fume
generation by the addition of Cs is shown in FIG. 8. When the Cs
content is less than 0.01%, the above effect is not obtained.
Meanwhile, over 1.0%, the amount of spatter generation is rather
increased and the hygroscopicity of flux is significantly enhanced,
to increase the generation amount of hydrogen in weld, thus
deteriorating the quality and the cracking resistance of the weld.
Accordingly, the Cs content is in the range of from 0.01 to
1.0%.
In addition, the sources of Cs include CsCO.sub.3, complex oxides
with SiO.sub.2 etc. and natural poilucite ore, and further the
single salt or complex salt obtained the synthesis of poilucite
ore. However, when the source of Cs is added in excess of 1.0% (Cs
converted value), the usability characteristics become extremely
poor.
TiO.sub.2 is expected to act as a slag forming agent and an arc
stabilizer. TiO.sub.2 is required to be added in an amount of 8% or
more to improve bead appearance/shape and arc stability in downward
or horizontal welding. However, when the TiO.sub.2 content is more
than 60%, the solidifying point of slag is increased, and the
viscosity of slag is excessively increased, tending to generate
slag inclusion and gas defect on the surface of bead. Accordingly,
the TiO.sub.2 content is in the range of from 8 to 60%.
In addition, the sources of TiO.sub.2 include oxides such as
rutile, reduced ilmenite, leucoxene, ilmenite and potassium
titanate.
Although the addition effect of single TiO.sub.2 or Cs is described
above, both effects are related to the respective added amounts.
Namely, the TiO.sub.2 /Cs ratio also exerts on the generation
amount of fume, bead sag in vertical upward welding, and quality in
X-ray inspection of weld (incomplete fusion, slag inclusion and the
like) (see FIG. 9). To obtain the excellent usability
characteristics in all positions, or to obtain good weld, the
TiO.sub.2 /Cs ratio must be in the range of 20 or more. However, it
exceeds 2000, the effect of reducing welding fume by the addition
of Cs is reduced and the quality in X-ray inspection of weld is
deteriorated. Accordingly, the TiO.sub.2 /Cs ratio is suppressed to
be 2000 or less.
In addition, compounds of alkali metals such as Li, Na and K, other
than Cs may be added in suitable amounts, if needed. The compounds
of these alkali metals, other than Cs, are very effective to
improve arc stability and to reduce the generation amount of
spatter; however, they also act as sources of significantly
generating welding fume. Namely, fluorides, carbonates, single
oxides such as Na.sub.2 O, K.sub.2 O and Li.sub.2 O of these alkali
metals act as the sources of significantly generating welding fume,
and even in the form of the complex oxides with other oxides, they
act also as the sources of generating welding fume. Accordingly,
the added amount of compounds of alkali metals other than Cs are
suppressed to be in the range of 7.0% or less (metal element
converted value).
In addition, other components, which are commonly added in the
titania based flux-cored wire, may be of course in this flux.
Moreover, the sheath metal is made of a common mild steel, and
particularly is made of a mild steel containing 0.02% or less of C
and 0.20% or less of Ti for reducing the amount of fume
generation.
The mild steel sheath further effective to reduce fume is made of a
mild steel containing, based on the weight of the total sheath,
0.01% or less of C, 0.01 to 0.10% of Ti, and 0.01 to 0.05% of Al,
the contents of Ti and C satisfying a relation of (Ti/C.gtoreq.3.0)
and the contents of Al and C satisfying a relation of
(Al.gtoreq.2.0).
Under the consideration of the workability in the rolling and/or
drawing process for wire fabrication, the other components are
limited such that Mn is in the range of from 0.10 to 0.70%, and Si
is 0.35% or less.
In general, the flux ratio is determined in combination with the
wire sectional shape, in terms of the uniformity in fusion of wire
and workability of the wire. The low flux ratio and the single
sectional shape are desirable for a small diameter wire; while a
high flux ratio and a complex sectional shape are desirable for a
large diameter wire. However, in either case, when the flux ratio
is less than 5%, spatter of large grain is increased; while, over
30%, the sheath is thinned, to lower wire feedability. Accordingly,
the flux ratio is in the range of from 5 to 30%.
(4) Reduction of fume mainly by adjustment of sheath composition
and flux composition (metal based)
Next, the reduction of fume mainly by adjustment of a mild steel
sheath composition and the metal based flux composition according
to the present invention will be described in detail.
The present inventors have found that the generation amount of fume
can be significantly reduced in a multiplier manner by suitably
controlling the contents of C, Ti and Al in a mild steel sheath,
and adding Cs and Rb as alkali metals in the metal based flux. The
experimental results will be described below.
In these experiments, flux-cored wires (diameter: 1.4 mm) were
fabricated using the metal based flux composition (flux ratio: 15%)
shown by No. 1 in Table 13 described later in combination with mild
steel sheaths (C: 0.003-0.03%, Mn: 0.20-0.30%, Si: 0.01-0.03%, P:
0.008-0.011%, S: 0.005-0.007%, N: 0.002-0.004%, and Ti and Al:
variable).
The wires thus obtained were used for performing a downward bead-on
plate welding test using a test plate (JIS G3106 SM490A, thickness:
12 mm) under the following welding conditions. The wires thus
obtained were tested under the following welding conditions for
examining the effect of reducing welding fume according to JIS
Z3930.
(Welding conditions)
Welding current: 350 A
Welding voltage: 36 V
Welding rate: 30 cm/min
Wire extension: 25 mm
Polarity: DCEP (wire: plus)
Shield gas: CO.sub.2 (flow rate: 25 l/min)
FIGS. 11 and 12 show relations between the generation amount of
welding fume and the contents of Ti, Al and C in a mild steel
sheath, which are obtained on the basis of the above experiments.
As will be apparent from FIGS. 11 and 12, with respect to the mild
steel sheath, the complex addition of Ti and Al in respective
amounts of 0.01% or more are effective to reduce the amount of fume
generation, in addition to the reduction of the C content according
to the conventional technique. Moreover, it is revealed that the
addition of only Al is a little effective; but the complex addition
of Al and Ti is significantly effective. Additionally, the addition
of Ti and Al becomes effective for reducing welding fume under the
conditions that C.ltoreq.0.02%, Ti/C.gtoreq.1.0%, and
Al/C.gtoreq.1.5%.
The reason why the addition of Ti and Al is effective for reducing
welding fume is that Ti and Al have high affinity with oxygen and
generate oxides having high solidifying points, to form an oxide
film on the surface of hanging droplet at the tip of a wire during
arc welding, thus suppressing the explosive generation of CO and
CO.sub.2, which is regarded as the source of fume generation,
caused by the reaction between O.sub.2 and C.
Moreover, the upper limits of Ti and Al must be Ti.ltoreq.0.20% and
Al.ltoreq.0.10% for avoiding the material deterioration such as
reduction in ductility and hardening caused by the yield thereof in
weld.
Additionally, as will be apparent from FIG. 13, the amount of
welding fume generation is significantly reduced by the addition of
Cs and Rb in the flux.
For this reason, a mild steel sheath suitable for reducing welding
fume contains, based on the weight of the total sheath, 0.02% or
less of C, 0.01 to 0.20% of Ti, and 0.01 to 0.10% of Al, the
contents of Ti and C satisfying a relation of (Ti/C.gtoreq.1.0) and
the contents of Al and C satisfying a relation of
(Al/C.gtoreq.1.5).
Preferably, the above mild steel contains 0.01% or less of C, 0.01
to 0.10% of Ti, and 0.01 to 0.05% of Al, the contents of Ti and C
satisfying a relation of (Ti/C.gtoreq.3.0) and the contents of Al
and C satisfying a relation of (Al/C.gtoreq.2.0).
In addition, under the consideration of the workability in the
rolling and/or drawing processes for wire fabrication, preferably,
the content of Mn is in the range of from 0.10 to 0.70% and the
content of Si is in the range of 0.35% or less.
The metal based flux composition suitable for reducing welding fume
contains, based on the weight of the total wire, 0.01 to 0.30%
(alkali metal converted value) of one or more kind of oxides and
fluorides of alkali metals excluding Cs and Rb, 5 to 28% of Fe
powder, 94% or more (based on the weight of the total wire) of
metal powder, and 0.001 to 0.10% (Cs or Rb converted value) of one
or two kinds of Cs and/or Rb; and further 0.5% to 3.60% of Mn
(including the Mn amount in the sheath) and 0.10 to 1.8% of Si
(including the Si content in the sheath).
In the above metal based flux, when the total amount of one or two
kinds of Cs and Rb is less than 0.001%, the effect of reducing
welding fume is not obtained (see FIG. 13). However, over 0.10%,
hygroscopicity is deteriorated, to reduce blowhole resistance and
increase the generation amount of diffusive hydrogen in weld,
thereby deteriorating cracking resistance. Cs and Rb are added in
the suitable form, and particularly, Cs is added in the form of
CsCO.sub.3 or in the form of complex oxides with TiO.sub.2 or
SiO.sub.2. The values of Cs and/or Rb are obtained by converting Cs
and/or Rb in the compound thereof into the elements. The content of
Cs and/or Rb is in the range of from 0.001 to 0.010%.
Alkali metals such as Li, Na and K (excluding Cs and Rb) are added
to reduce arc stability and amount of spatter generation. Alkali
metals are significantly large in hygroscopicity; accordingly, they
are desirable to be added by one or more kinds in the form of
oxides or fluorides. The reason why the contents of alkali metals
are specified in the above range is as follows. Namely, when the
content of alkali metals is less than 0.01%, the effects to improve
arc stability and to reduce the amount of spatter generation cannot
be obtained. Meanwhile, when being more than 0.30%, the amount of
spatter generation is rather increased and the fume reducing effect
by the addition of Ti and Al is not obtained, because alkali metals
are high in vapor pressure.
In addition, feldspar, sodium silicate anhydride, water glass,
complex oxides of Li, Na, K and the like, cryolite, fluorides such
as potassium silicofluoride, sodium silicofluoride, and carbonates
of alkali metals in small amounts are similarly effective, since
they are dissolved by welding arc into oxides. The added amount of
the present invention is converted into the alkali metal element,
and is preferably in the range of from 0.01 to 0.10%.
Fe powder is added according to the flux ratio, to obtain a high
deposition rate. When the flux ratio (% based on the weight of the
total wire) is less than 10%, spatter of large grain is increased
because the wall thickness of the sheath is excessively thick.
Meanwhile, over 30%, the wire is softened along with the reduction
in the wall thickness of the sheath, to lower the feedability of
the wire; and arc is significantly expanded, tending to reduce
penetration depth and to generate undercut. Accordingly, the flux
ratio is preferably in the range of from 10 to 30%.
Fe powder is added according to the above flux ratio; however, less
than 5%, it is difficult to obtain a high deposition rate which is
regarded as the feature of the metal based flux-cored wire.
Meanwhile, over 28%, the other components such as a deoxidizing
agent are insufficient, which makes it difficult to secure the
specified mechanical properties of weld and prevent weld defects
such as blowhole. Accordingly, Fe powder is specified to be in the
range of from 5 to 28%.
To secure the high deposition rate as the feature of the metal
based flux-cored wire and the slag amount sufficient for continuous
multi-layer welding, the metal powder ratio in the flux excluding
non-metals such as oxide, fluoride and carbonate, must be in the
range of 94% or more.
Mn is added in the flux under the consideration of the Mn content
in the sheath, to act as a deoxidizing agent, to improve strength
and toughness by enhancement of hardenability, and to improve bead
shape (especially in horizontal fillet welding) due to an increase
in the viscosity of molten metal slag. In this case, when the Mn
content is less than 0.5%, sufficient strength for mild steel is
not obtained, and bead shape is poor. Meanwhile, over 3.6%, the
strength of weld is excessively increased, tending to generate low
temperature cracking. Accordingly, the Mn content is in the range
of 0.5 to 3.6%, preferably, from 0.5 to 2.5%. The sources of Mn
include Mn, Fe-Mn, Fe-Si-Mn and the like.
Si has the function and effect similar to those of Mn. However,
when the Si content is less than 0.1%, it is not effective to act
as an deoxidizing agent, to enhance toughness, and to improve bead
shape. Meanwhile, over 1.8%, the yield of Si in weld is excessively
large, to lower toughness and ductility. Accordingly, the Si
content is in the range of from 0.1 to 1.8, preferably, from 0.3 to
1.2%. The sources of Si include metal Si, and alloys such as Fe-Si,
Fe-Si-Mn, and Fe-Si-Mg.
Moreover, within the range of satisfying the above ratio of metal
powder, oxides such as SiO.sub.2, ZrO.sub.2, CaO and FeO may be
added to further improve the bead appearance/shape; and both
bismuth oxide (Bi.sub.2 O.sub.3) in an amount of 0.1% or less
(based on the weight of the total wire) not to generate high
temperature cracking, and MgO or Mg in an amount of 0.2% or less
(based on the weight of the total wire) not to deteriorate the bead
shape, may be added to improve slag removability.
Additionally, the kinds of base steels to which the present
invention is applied mainly include mild steel and high tensile
steel; however, by the addition of Ni, Cr, Mo and Cu and alloys
thereof, the application range may be extended to low alloy steel
and high alloy steel.
The flux-cored wire described above is not limited to its wire
sectional shape, and uses various shapes shown in (A) to (D) of
FIG. 10. Moreover, the surface of a wire may be applied with
plating of Cu or Al to a thickness of 0.05 to 0.35%. The wire
diameter may be freely selected according to the application.
The examples of shield gases include oxidizing gas, natural gas and
reducing gas. As the common shield gas, there may be used a
CO.sub.2 gas or a mixed gas of two kinds of Ar, CO.sub.2, O.sub.2
and He.
The present invention will be more clearly understood with
reference to the following examples.
EXAMPLE 1
This example is performed to examine the effect of reducing the
fume mainly by adjustment of the sheath composition, in combination
with the preferred metal based flux composition.
Flux-cored wires (diameter: 1.4 mm) having a sectional shape shown
in (A) of FIG. 10 were fabricated, using steel sheaths having the
chemical compositions shown in Table 1, in which fluxes having the
compositions shown in tables 2 and 3 were filled. Next, each
flux-cored wire was used for performing a welding test under the
following conditions for examining the amount of fume generation
and the usability characteristics.
(Welding Condition)
Polarity: DCEP (wire: plus)
Welding current: 350 A
Welding voltage: 37.+-.3 V
Welding rate: 30 cm/min
Shield gas: 100% CO.sub.2 (flow rate: 25l/min)
Distance between tip and base metal: 25 mm
Test plate: JIS G3106, SM490A (thickness: 12 mm)
Welding process: downward bead-on plate welding
(Measurement for Fume)
In accordance with JIS Z 3930 "Method of Measuring Total Fume
Amount of Covered Electrode", the value per time (g/min) (average
value, repeated number: 3) was obtained by measuring the weight of
fume generated during welding for 1 min. The fume was collected by
an apparatus provided with a collecting box shown in FIG. 3.
(Usability Characteristics)
This was evaluated by sensory analysis.
From the results shown in Table 4, the following considerations
were made.
Wire Nos. 1 to 8 are cases where the sheath compositions are
suitably adjusted, in which the amount of fume generation is
extremely reduced.
On the contrary, Wire Nos, 9 to 16 are cases where either of the
sheath components is not suitable.
Concretely, Wire No. 9 is a case where the C content is larger, in
which the amount of fume generation is increased. Wire Nos. 10 and
11 are cases where the Ti content in the sheath is not suitable. In
these wires, when the Ti content is smaller, the amount of fume
generation is increased, while when it is larger, the yield in weld
is increased to lower the toughness. Wire Nos. 12 and 13 are cases
where the Al content is not suitable. In these wires, when the Al
content is smaller, the amount of fume generation is increased;
while when it is larger, the toughness of weld is lowered. Wire No.
14 is not suitable in the Ti/C ratio of the sheath, and Wire No. 15
is not suitable in the Al/C ratio of the sheath, with a result that
the amount of fume generation is increased. Wire No. 16 is not
suitable in the contents of C, Ti and Al, and further the Ti/C
ratio and the Al/C ratio, in which the amount of fume generation is
significantly increased.
Moreover, Wire Nos. 17 to 30 are cases where the sheath
compositions are suitably adjusted but the metal based flux
compositions are not suitably adjusted.
Concretely, Wire Nos. 17 and 18 are cases where the contents of Ti
or Ti oxide (Ti converted value) in the flux is not suitable. In
these case, when it is smaller, the amount of fume generation is
increased and arc stability is deteriorated, while when it is
larger, the toughness of weld is lowered. Wire No. 19 is a case
where the Al content is not suitable, with a result that the
ductility of weld is lowered. Wire No. 20 is a case where the Ti/C
ratio is not suitable, in which the effect of reducing fume is not
obtained. Wire No. 21 is a case where the C content is out of the
scope of the present invention, with a result that the amount of
fume generation is increased. Wire Nos. 22 and 23 are cases where
the contents of alkali metals are not suitable. In these cases,
when they are smaller, arc stability is deteriorated and the amount
of spatter generation is increased, while when they are larger, the
amount of spatter generation is increased and the effect of
reducing fume is harmed. Wire Nos. 24 and 25 are cases where the Fe
content in the flux is not suitable. In these cases, when it
smaller, spatter of large grain is increased; while when it is
larger, the wall thickness of the sheath is thinned, to deteriorate
feedability, tending to generate weld defects such as undercut.
Wire No. 26 is a case where the ratio of metal powder is not
suitable, in which the efficiency as the feature of the metal based
flux-cored wire is harmed, and the amount of slag generation is
increased thereby making difficult continuous multi-layer welding.
Wire Nos. 27 and 28 are cases where the Mn content is not suitable.
In these cases, when it is smaller, sufficient strength is not
obtained and bead shape is deteriorated, while when it is larger,
strength is excessively increased thus tending to generate low
temperature cracking. Wire Nos. 29 and 30 are cases where the Si
content is not suitable. In these cases, when it is smaller, bead
shape is deteriorated, while when it is larger, the toughness and
ductility of weld are lowered.
Moreover, Wire No. 31 is a case where all of the requirements
contributing to the reduction in the amount of fume generation (the
contents of C, Ti and Al, and further the Ti/C and Al/C in the
flux; and the contents of Ti and C and further the Ti/C in the
sheath) are not suitable, in which the generation amount of fume is
significantly increased.
TABLE 1 ______________________________________ Sheath Metal
Composition (wt %) No. C Si Mn Ti Al Ti/C Al/C
______________________________________ 1 0.005 0.02 0.25 0.06 0.04
12.0 8.0 2 0.015 " 0.20 0.05 0.03 3.3 2.0 3 0.010 " " 0.15 0.06
15.0 6.0 4 " " " 0.04 0.02 4.0 2.0 5 0.005 " 0.25 0.06 0.04 12.0
8.0 6 " " " " " " " 7 " " " " " " " 8 " " " " " " " 9 0.025 " " " "
2.4 1.8 10 0.005 " " 0.005 " 1.0 8.0 11 " " " 0.22 " 44.0 " 12 " "
" 0.06 0.008 12.0 1.6 13 " " " " 0.12 " 24.0 14 0.018 " " 0.015
0.04 0.8 2.2 15 " " " 0.06 0.02 3.3 1.1 16 0.022 " " 0.005 0.005
0.2 0.2 17 0.005 " " 0.06 0.04 12.0 8.0 18 " " " " " " " 19 " " " "
" " " 20 " " " " " " " 21 " " " " " " " 22 " " " " " " " 23 " " " "
" " " 24 " " " " " " " 25 " " " " " " " 26 " " " " " " " 27 " " " "
" " " 28 " " " " " " " 29 " " " " " " " 30 " " " " " " " 31 0.022 "
" 0.005 0.005 0.2 0.2 ______________________________________
TABLE 2
__________________________________________________________________________
Metal Powder Flux Composition (wt % based on total wire) Ratio (%)
No. Ti TiO.sub.2 Al Al.sub.2 O.sub.3 C Mn Si NaF SiO.sub.2 K.sub.2
O Fe Powder Ti/C (to Flux)
__________________________________________________________________________
1 0.14 0.25 0.10 0.10 0.02 2.01 0.96 -- 0.14 0.03 11.25 14.5 96.5 2
" " " " " " " -- " " " " " 3 " " " " " " " -- " " " " " 4 " " " " "
" " -- " " " " " 5 " " " " 0.05 1.50 1.0 -- " " 11.69 5.8 " 6 0.30
" 0.20 " 0.02 2.00 0.80 0.01 " " 11.15 22.5 " 7 0.10 0.10 " 0.50
0.06 2.10 0.90 " 0.20 0.05 10.78 2.7 94.3 8 0.14 0.25 0.10 0.10
0.02 2.01 0.96 -- 0.14 0.03 16.25 14.5 97.4 9 " " " " " " " -- " "
11.25 " 96.5 10 " " " " " " " -- " " " " " 11 " " " " " " " -- " "
" " " 12 " " " " " " " -- " " " " " 13 " " " " " " " -- " " " " "
14 " " " " " " " -- " " " " " 15 " " " " " " " -- " " " " " 16 " "
" " " " " -- " " " " "
__________________________________________________________________________
(Note) Wire Nos. correspond to those in Table 1.
TABLE 3
__________________________________________________________________________
Metal Powder Flux Composition (wt % based on total wire) Ratio (%)
No. Ti TiO.sub.2 Al Al.sub.2 O.sub.3 C Mn Si NaF SiO.sub.2 K.sub.2
O Fe Powder Ti/C (to Flux)
__________________________________________________________________________
17 0.01 -- 0.10 0.10 0.01 2.01 0.96 -- 0.14 0.03 11.64 1.0 98.2 18
1.2 -- " " 0.02 " " -- " " 10.44 60.0 " 19 0.14 0.25 1.2 -- " " "
-- " " 10.25 14.5 97.2 20 0.04 -- 0.10 0.10 0.05 " " -- " " 11.57
0.8 98.2 21 0.14 0.25 " " 0.08 " " -- " " 11.18 3.6 " 22 " " " "
0.02 " " -- " 0.01 11.27 14.5 96.7 23 " " " " " " " 0.01 " 0.20
11.07 " 95.3 24 " -- " -- " " " -- " 0.03 4.6 7.0 97.9 25 " 0.25 "
0.10 " " " -- " " 29.25 14.5 98.4 26 " 0.40 " 0.50 " " " -- " "
10.7 19.0 92.9 27 " 0.25 " 0.10 " 0.20 " -- " " 13.06 14.5 96.5 28
" " " " " 3.70 " -- " " 9.56 " " 29 " " " " " 2.01 0.05 -- " "
12.16 " " 30 " " " " " " 1.90 -- " " 10.31 " " 31 0.01 -- " " 0.08
" 0.96 -- " " 11.57 0.1 98.2
__________________________________________________________________________
(Note) Wire Nos. correspond to those in Table 1.
TABLE 4 ______________________________________ Usability
Characteristics, Efficiency, Fume Generation Welding Performance or
the like No. Amount (mg/min) Item Determination
______________________________________ 1 505 -- -- 2 520 -- -- 3
508 -- -- 4 530 -- -- 5 510 -- -- 6 490 -- -- 7 515 -- -- 8 500 --
-- 9 610 -- -- 10 810 -- -- 11 485 Ductility x 12 700 -- -- 13 480
Ductility x 14 712 -- -- 15 617 -- -- 16 931 -- -- 17 604 -- -- 18
511 Ductility x 19 502 " x 20 605 -- -- 21 600 -- -- 22 507 Spatter
(arc stability) .DELTA. 23 590 Spatter .DELTA. 24 520 Spatter
(large grain) x 25 513 Feedability .DELTA. 26 512 Efficiency
.DELTA. 27 535 Strength, Bead Shape x 28 496 Strength, Cracking
.DELTA. 29 529 Bead Shape x 30 510 Toughness, Ductility x 31 1020
-- -- ______________________________________
EXAMPLE 2
This example is performed to examine the effect of reducing the
fume mainly by adjustment of the sheath composition, in combination
of the preferred titania based flux composition.
Flux-cored wires (diameter: 1.2 mm) having a sectional shape shown
in (A) of FIG. 10 were fabricated, using steel sheaths having the
chemical compositions shown in Table 5, in which fluxes having the
compositions shown in Table 6 were filled. Next, each flux-cored
wire was used for performing a welding test under the following
conditions for examining the generation amount of fume and the
usability characteristics.
(Welding Condition)
Polarity: DCEP (wire: plus)
Welding current: 280 A
Welding voltage: 30 V
Welding rate: 30 cm/min
Shield gas: 100% CO.sub.2 (flow rate: 25 l/min)
Distance between tip and base metal: 25 mm
Test plate: JIS G3106, SM490A (thickness: 12 mm)
Welding process: horizontal fillet welding
(Measurement for Fume)
In accordance with JIS Z 3930 "Method of Measuring Total Fume
Amount of Covered Electrode", the value per time (g/min) (average
value, repeated number: 3) was obtained by measuring the weight of
fume generated during welding for 1 min. The fume was collected by
an apparatus provided with a collecting box shown in FIG. 3.
(Usability Characteristics)
This was evaluated by sensory analysis.
From the results shown in Table 7, the following considerations
were made.
Wire Nos. 1 to 8 are cases where the sheath compositions are
suitably adjusted, in which the amount of fume generation is
lowered and the usability characteristics are desirable.
On the contrary, Wire No. 9 is a case where the Ti/C of the sheath
is not suitable, with a result that the amount of fume generation
is increased. Wire No. 10 is a case where Al/C of the sheath is not
suitable, with a result that the amount of fume generation is
significantly increased.
Moreover, Wire Nos. 11 to 15 are cases where the sheath
compositions are suitably adjusted but the titania based flux
compositions are not suitably adjusted.
Concretely, Wire No. 11 is a case where the content of TiO.sub.2 in
the flux is larger, in which the generation amount of fume is small
but weld defects (slag inclusion) are generated. Wire No. 12 is a
case where the content of TiO.sub.2 in the flux is smaller, in
which the amount of fume generation is small but the ability of
covering the surface of bead is insufficient, to deteriorate bead
appearance. Wire No. 13 is a case where the content of the oxide of
alkali metal (NaAlSi.sub.3 O.sub.9) is smaller, in which the amount
of fume generation is small but slag removability is deteriorated.
Wire No. 14 is a case where the Mg content in the flux is larger,
with a result that the amount of fume generation is increased. Wire
No. 15 is a case where the C content in the flux is larger, in
which the amount of fume generation is significantly increased and
the generation of spatter is also increased.
TABLE 5 ______________________________________ Sheath Metal
Composition (wt %) No. C Si Mn Ti Al Ti/C Al/C
______________________________________ 1 0.003 0.01 0.25 0.050
0.048 16.7 16.0 2 " " " " " " " 3 " " " " " " " 4 0.020 " " 0.042
0.040 2.1 2.0 5 0.003 " " 0.050 0.084 3.3 3.3 6 " " " " " " " 7
0.015 0.02 " 0.015 0.040 1.0 2.7 8 0.018 " " 0.03 0.027 1.7 1.5 9
0.018 " " 0.010 0.051 0.6 2.8 10 0.030 " " 0.030 0.036 1.0 1.2 11
0.003 0.01 " 0.050 0.048 16.7 16.0 12 " " " " " " " 13 " " " " " "
" 14 " " " " " " " 15 " " " " " " "
______________________________________
TABLE 6
__________________________________________________________________________
Flux Composition (wt % based on total wire) MgO Fe ZrO.sub.2,
Al.sub.2 O.sub.3 No. TiO.sub.2 NaAlSi.sub.3 O.sub.8 KAlSi.sub.3
O.sub.8 C Mn Si Mg (Mg converted value) Powder Other Oxides Total
__________________________________________________________________________
1 1.00 1.50 -- 0.04 2.40 0.70 -- -- 5.60 3.76 15.0 2 8.50 0.01 -- "
2.50 0.60 -- -- 2.85 0.50 " 3 5.50 0.04 -- 0.03 " " -- -- 3.33 3.00
" 4 " " -- 0.06 " " -- -- 3.30 " " 5 " 0.02 0.02 0.04 " " -- 0.01
3.31 " " 6 " " " " " " 0.09 -- 3.23 " " 7 " -- 0.04 " " " -- --
3.32 " " 8 " -- " " " " -- -- " " " 9 " -- " " " " -- -- " " " 10 "
-- " " " " -- -- " " " 11 9.00 0.01 -- " " " -- -- 2.35 0.50 " 12
0.50 1.00 -- " 2.40 0.70 -- -- 6.60 3.76 " 13 5.00 1.60 -- " 2.50
0.60 -- -- 1.76 3.00 " 14 " 0.30 0.30 " " " 1.10 -- 1.66 " " 15 " "
" 0.08 " " -- -- 2.73 " "
__________________________________________________________________________
TABLE 7 ______________________________________ Usability
Characteristics Fume Bead Slag Amount Slag Generation Wire
Appearance/ Remov- of Inclusion Amount No. Shape ability Spatter at
Root (mg/min) ______________________________________ 1
.smallcircle. .smallcircle. .circleincircle. .circleincircle. 470 2
.circleincircle. .smallcircle. .circleincircle. .smallcircle. 520 3
.circleincircle. .smallcircle. .circleincircle. .circleincircle.
480 4 .circleincircle. .smallcircle. .smallcircle. .circleincircle.
690 5 .circleincircle. .circleincircle. .circleincircle.
.circleincircle. 525 6 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. 700 7 .circleincircle.
.smallcircle. .circleincircle. .circleincircle. 695 8
.circleincircle. .smallcircle. .circleincircle. .circleincircle.
695 9 .circleincircle. .smallcircle. .circleincircle.
.circleincircle. 815 10 .circleincircle. .smallcircle.
.circleincircle. .circleincircle. 900 11 .circleincircle.
.smallcircle. .smallcircle. x 530 12 .DELTA. .smallcircle.
.circleincircle. .circleincircle. 480 13 .circleincircle. .DELTA.
.circleincircle. .circleincircle. 515 14 .circleincircle.
.circleincircle. .DELTA. .circleincircle. 860 15 .circleincircle.
.smallcircle. .DELTA. .circleincircle. 780
______________________________________ (Note) Evaluation of
usability characteristics: .circleincircle. (very good),
.smallcircle. (good), .DELTA. (slightly poor), x (poor)
EXAMPLE 3
This example is performed to examine the effect of reducing the
fume mainly by adjustment of the metal based flux composition.
Flux-cored wires (diameter: 1.2 mm) having a sectional shape shown
in (A) of FIG. 10 were fabricated, using steel sheaths having the
chemical compositions shown in Table 8, in which fluxes having the
composition shown in Table 9 were filled. Next, each flux-cored
wire was used for performing a welding test under the following
conditions for examining the amount of fume generation and the
usability characteristics.
(Welding Condition)
Polarity: DCEP (wire: plus)
Welding current: 300 A
Welding voltage: suitable (arc extension: 1.5 mm from surface of
base material)
Welding rate: 30 cm/min
Shield gas: 100% CO.sub.2 (flow rate: 25 l/min)
Distance between tip and base metal: 25 mm
Test plate: JIS G3106, SM490A (thickness: 12 mm)
Welding process: downward bead-on plate welding
(Measurement for Fume)
In accordance with JIS Z 3930 "Method of Measuring Total Fume
Amount of Covered Electrode", the value per time (g/min) (average
value, repeated number: 3) was obtained by measuring the weight of
fume generated during welding for 1 min. The fume was collected by
an apparatus provided with a collecting box shown in FIG. 3.
(Usability Characteristics)
This was evaluated by sensory analysis.
From the results shown in Table 10, the following considerations
were made.
Wire Nos. 1 to 7 are cases where the flux compositions are suitably
adjusted, in which the amount of fume generation is extremely
reduced (about one-half that of the conventional wire).
On the contrary, Wire Nos. 8 to 19 are cases where the metal based
flux compositions are not suitably adjusted.
Concretely, Wire Nos. 17 and 18 are cases where three requirements
for reducing welding fume (the contents of C, Ti and Cs and/or Rb)
are not satisfied, in which the generation amount of fume is
extremely increased. Wire No. 8 is a case where the C content is
not suitable, with a result that the amount of fume generation is
increased. Wire Nos. 9 and 10 are cases where the Ti content is not
suitable. In these cases, when the Ti content is smaller, the
amount of fume generation is increased, while when it is larger,
there occurs a problem in terms of cracking resistance. Wire Nos.
11 and 12 are cases where the contents of Cs and/or Rb are not
suitable. In these cases, when the content of Cs and/or Rb is
smaller, the amount of fume generation is increased, while when it
is larger, the hygroscopicity of the wire is deteriorated, to lower
blowhole resistance and cracking resistance. Wire Nos. 13 and 14
are cases where the flux ratio is not suitable. In these cases,
when the flux ratio is smaller, spatter of large grain is
increased, while when it is larger, feedability is deteriorated.
Wire Nos. 15 and 19 are cases where the content of Fe powder is not
suitable. In these cases, when the content of Fe powder is smaller,
the efficiency is deteriorated, while when it is large, the other
components (deoxidizing agent, etc.) are insufficient, to generate
weld defects such as pit and blowhole. Wire No. 17 is a case where
the content of [{C/(Cs+Rb)}+Ti] is not suitable, in which the
penetration depth is insufficient, tending to generate defects in
groove welding.
TABLE 8 ______________________________________ Sheath Metal (Steel)
Composition (wt %) Symbol C Si Mn Al Ti Ti/C
______________________________________ A 0.02 <0.01 0.25 0.03
0.01 0.5 B 0.005 <0.01 0.25 0.03 0.05 10
______________________________________
TABLE 9
__________________________________________________________________________
Sample Wire Flux Composition (wt %) Sheath Flux Metal Fe Equation
Ratio No. C Mn Si Al Ti Cs.sub.2 SiO.sub.2 Cs.sub.2 CO.sub.3
Rb.sub.2 CO.sub.3 TiO.sub.2 Na.sub.2 SiO.sub.3 SiO.sub.2 Powder (1)
(%) Symbol
__________________________________________________________________________
1 0.2 12 6 0.5 2 -- 0.1 -- 2 1 0.5 75.6 5.7 20 A 2 " " " " " -- "
-- " " " " " " B 3 " " " " " 0.1 -- 0.1 " 2 1 74.3 4.5 " A 4 0.1 15
10 2 1 -- 0.2 -- 3 " 1 65.7 3.4 " " 5 0.4 " " 1 3 0.3 -- -- 1 " "
66.3 5.2 15 " 6 0.3 " " 2 0.5 -- 0.05 -- " " " 68.15 8.5 " " 7 " "
" " " -- " -- " " " " " " B 8 0.6 12 6 0.5 2 -- 0.1 -- 2 1 0.5 75.3
10.6 20 A 9 0.2 " " " 0.2 -- " -- " " " 77.4 3.9 " " 10 " " " " 3.3
-- " -- " " " 74.3 7.0 " " 11 " " " " 2 -- 0.01 -- " " " 75.69 27.9
" " 12 " " " " " -- 0.33 -- " " " 75.37 3.9 " " 13 " " " " " -- 0.1
-- " " " 75.6 5.7 8 " 14 " " " " " -- " -- " " " " " 32 " 15 " 15
10 2 2 -- " -- 5 5 2.2 58.5 6.2 20 " 16 0.1 12 6 0.5 0.5 -- 0.2 --
2 1 0.5 77.2 2.3 " " 17 0.6 " " " 0.2 -- 0.01 -- " " " 77.19 75.3 "
" 18 " " " " " -- " -- " " " " " " B 19 0.2 5 3 0.2 0.5 -- 0.1 -- "
" " 87.5 4.2 " A
__________________________________________________________________________
(Note) Equation (1) = {C/(Cs + Rb)} + Ti
TABLE 10 ______________________________________ Fume Generation
Amount Others No. (mg/min) Item Determination
______________________________________ 1 350 -- -- 2 320 -- -- 3
310 -- -- 4 300 -- -- 5 368 -- -- 6 360 -- -- 7 340 -- -- 8 510 --
-- 9 450 -- -- 10 335 Cracking Resistance .DELTA. 11 472 -- -- 12
306 Moisture Absorption x Resistance 13 330 Spatter .DELTA. 14 355
Feedability x 15 321 Efficiency .DELTA. 16 336 Penetration .DELTA.
17 810 -- -- 18 783 -- -- 19 347 Quality in X-ray Inspection x
______________________________________
EXAMPLE 4
This example is performed to examine the effect of reducing the
fume mainly by adjustment of the titania based flux
composition.
Flux-cored wires (diameter: 1.2 mm) were fabricated, using steel
sheaths having the chemical compositions shown in Table 11, in
which fluxes having the compositions shown in Table 11 were filled
at a specified flux ratio. Next, each flux-cored wire was used for
performing a welding test under the following conditions for
examining the amount of fume generation and the usability
characteristics.
(Welding Condition)
Polarity: DCEP (wire: plus)
Welding current: 300 A
Arc voltage: suitable voltage to obtain arc extension of 1.5 to 2.0
mm
Welding rate: 30 cm/min
Wire extension: 25 mm
Shield gas: 100% CO.sub.2 (flow rate: 25 l/min)
Test plate: JIS G3106, SM490A (thickness: 12 mm)
Welding process: downward bead-on plate welding
(Measurement for Fume)
In accordance with JIS Z 3930 "Method of Measuring Total Fume
Amount of Covered Electrode", the value per time (g/min) (average
value, repeated number: 3) was obtained by measuring the weight of
fume generated during welding for 1 min. The fume was collected by
an apparatus provided with a collecting box shown in FIG. 3.
(Usability Characteristics)
This was evaluated by sensory analysis.
From the results shown in Table 1, the following considerations
were made.
Wire Nos. 2 to 5, 8 to 10, 15 and 16, 19 and 20 are cases where the
titania based flux compositions are suitably adjusted, in which the
amount of fume generation is significantly reduced and the
usability characteristics (generation amount of spatter, bead sag,
quality in X-ray inspection, bead appearance, etc.) are
excellent.
On the contrary, the other wires are cases where the flux
compositions are not suitable, in which the amount of fume
generation is increased, and the usability characteristics are poor
in some wires.
In addition, Wire Nos. 1 to 6 are made to examine the effect of the
content of Ti in the flux; Wire Nos. 7 to 11 are for the effect of
the Cs content in the flux; Wire Nos. 12 and 13 are for the effect
of the C content in the flux; Wire Nos. 14 to 17 are for the effect
of the content of TiO.sub.2 in the flux; Wire Nos. 18 to 21 are for
the effect of the flux ratio; and Wire Nos. 22 and 23 are for the
effect of the contents of C and Ti in the steel sheath.
TABLE 11
__________________________________________________________________________
Usability Characteristics Fume Flux Composition Flux Hoop
Composition (wt % Spatter Quality in Bead Generation Wire (wt %
based on total flux) Ratio based on total sheath) Generation Bead
X-ray Appearance/ Amount No. TiO.sub.2 Cs C TiO.sub.2 /Cs (%) C Ti
Amount Sag Inspection Shape (mg/min)
__________________________________________________________________________
1 6 0.3 0.2 23 10 0.01 0.05 .DELTA. x .circleincircle. .DELTA. 700
2 8 0.4 0.1 20 15 0.02 0.03 .smallcircle. .smallcircle.
.circleincircle. .smallcircle. 600 3 10 0.05 0.3 200 20 0.01 0.10
.smallcircle. .smallcircle. .circleincircle. .smallcircle. 580 4 40
0.05 0.2 800 20 tr tr .circleincircle. .circleincircle.
.circleincircle. .circleincircle. 470 5 57 0.8 0.5 71 8 0.02 tr
.circleincircle. .circleincircle. .smallcircle. .smallcircle. 530 6
62 0.08 0.3 775 25 0.01 0.13 .smallcircle. .circleincircle. .DELTA.
.DELTA. 740 7 20 0.008 0.4 2500 15 0.01 tr .smallcircle.
.smallcircle. .smallcircle. .smallcircle. 920 8 10 0.013 0.2 769 18
0.01 0.15 .smallcircle. .smallcircle. .circleincircle.
.smallcircle. 630 9 30 0.6 0.05 50 20 0.02 0.03 .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 480 10 50 0.9
0.03 56 10 0.01 0.17 .circleincircle. .smallcircle. .smallcircle.
.smallcircle. 500 11 40 1.2 0.3 33 23 0.01 0.01 .DELTA.-x .DELTA.
.smallcircle. .smallcircle. 450 12 30 0.04 0.6 750 9 0.1 0.06
.DELTA.-x .smallcircle. .smallcircle. .DELTA. 740 13 55 0.5 0.9 110
27 0.04 0.05 x .smallcircle. .smallcircle. .DELTA. 880 14 17 0.94
0.1 18 15 0.01 tr .DELTA. .DELTA. .DELTA. .DELTA. 820 15 20 0.95
0.4 21 12 0.01 0.03 .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 520 16 59 0.03 0.2 1967 25 0.01 tr .smallcircle.
.circleincircle. .smallcircle. .smallcircle. 680 17 41 0.02 0.2
2050 17 0.02 0.08 .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 780 18 40 0.5 0.1 80 3 0.01 tr .DELTA. .DELTA.
.smallcircle. .DELTA. 750 19 47 0.7 0.2 67 6 0.005 0.04
.smallcircle. .smallcircle. .smallcircle. .smallcircle. 580 20 12
0.05 0.3 240 29 0.01 tr .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 540 21 23 0.4 0.4 58 32 0.01 0.05 .smallcircle.
.smallcircle. .DELTA. .DELTA. 620 22 30 0.05 0.1 600 20 0.03 tr
.DELTA. .smallcircle. .smallcircle. .smallcircle. 740 23 38 0.1
0.05 760 15 0.01 0.22 -- -- -- -- --
__________________________________________________________________________
(Note 1) Evaluation: x (poor), .DELTA. (slightly poor),
.smallcircle. (good), .circleincircle. (very good) (Note 2) No. 21
was high in the frequency of breakage, and No. 23 was difficult to
be drawn.
EXAMPLE 5
This example is performed to examine the effect of reducing the
fume mainly by adjustment of the sheath metal composition and the
metal based flux composition.
Flux-cored wires (diameter: 1.4 mm) having a sectional shape shown
in (A) of FIG. 10 were fabricated, using steel sheaths having the
chemical compositions shown in Table 12, in which fluxes having the
composition shown in Table 13 were filled. Next, each flux-cored
wire was used for performing a welding test under the following
conditions for examining the amount of fume generation and the
usability characteristics.
(Welding Condition)
Polarity: DCEP (wire: plus)
Welding current: 350 A
Welding voltage: 37.+-.3 V
Welding rate: 30 cm/min
Shield gas: 100% CO.sub.2 (flow rate: 25 l/min)
Distance between tip and base metal: 25 mm
Test plate: JIS G3106, SM490A (thickness: 12 mm)
Welding process: downward bead-on plate welding
(Measurement for Fume)
In accordance with JIS Z 3930 "Method of Measuring Total Fume
Amount of Covered Electrode", the value per time (g/min) (average
value, repeated number: 3) was obtained by measuring the weight of
fume generated during welding for 1 min. The fume was collected by
an apparatus provided with a collecting box shown in FIG. 3.
(Usability Characteristics)
This was evaluated by sensory analysis.
From the results shown in Table 14, the following considerations
were made.
Wire Nos. 2, 3, 6, 7, 15 and 18 are cases where the sheath
compositions and the flux compositions are suitably adjusted, in
which the amount of fume generation is significantly reduced.
On the contrary, the other wires are case where either of the
sheath composition and the flux composition is not suitable, in
which the amount of fume generation is increased, or if it is not
reduced, the other performances such as the usability
characteristics are deteriorated.
Concretely, Wire Nos. 1 and 4 are cases where the contents of Cs
and Rb are not suitable. In these cases, when the contents of Cs
and Rb are smaller, the amount of fume generation is increased,
while when they are larger, the hygroscopicity of the wire is
deteriorated, to lower blowhole resistance and the cracking
resistance. Wire Nos. 5 and 8 are cases where the contents of
alkali metals are not suitable. In these cases, when the contents
of alkali metals are smaller, arc stability is deteriorated, to
increase the generation amount of spatter, while when they are
larger, the amount of spatter generation is rather increased and
also the effect of reducing the amount of fume generation is
harmed.
Wire Nos. 9 and 10 are cases where the content of Fe powder is not
suitable. In these cases, when the content of Fe powder is smaller,
the welding efficiency is lowered and the amount of spatter
generation is increased, while when it is larger, it is difficult
to secure the mechanical properties of weld and to prevent weld
defects such as pit and blowhole. Wire Nos. 11 and 12 are cases
where the Mn content is not suitable. In these cases, when the Mn
content is smaller, sufficient strength is not obtained and bead
shape is deteriorated, while when it is larger, strength is
excessively increased, tending to generate low temperature
cracking. Wire Nos. 13 and 14 are cases where the Si content is not
suitable. In these cases, when the Si content is smaller, bead
shape is deteriorated, while when it is larger, the toughness and
ductility of weld are lowered.
Wire No. 16 is a case where the C content in the sheath is not
suitable, in which the amount of fume generation is increased. Wire
Nos. 17 and 21 are cases where the Al content in the sheath is not
suitable. In these cases, when the Al content is smaller, the
amount of fume generation is increased, while when it is larger,
the ductility of weld is lowered. Wire Nos. 19 and 20 are cases
where the Ti amount in the sheath is not suitable. In these cases,
when the Ti amount is smaller, the amount of fume generation is
increased, while when it is larger, the yield of Ti in weld is
increased, to lower the toughness.
TABLE 12 ______________________________________ Sheath Metal
Composition (wt %) No. C Si Mn Ti Al Ti/C Al/C
______________________________________ 1 0.005 0.02 0.25 0.06 0.04
12.0 8.0 2 0.018 " " 0.02 " 1.1 2.2 3 0.015 " " 0.06 " 2.4 1.8 4
0.005 " 0.30 0.06 0.007 12.0 1.4 5 0.007 " 0.20 0.05 0.012 7.1 1.7
6 0.009 0.01 0.32 0.008 0.03 0.9 3.3 7 0.010 " 0.21 0.23 0.04 23.0
4.0 8 0.006 " 0.18 0.03 0.13 5.0 21.7 9 0.003 " 0.25 0.05 0.04 16.7
13.3 10 0.030 " " " " 1.7 1.3
______________________________________
TABLE 13
__________________________________________________________________________
Metal Wire Com- Flux Composition Powder position Sheath Metal
Symbols (wt % based on total flux, alkali metal converted value)
Ratio (%) (wt %) (corresponding to No. CsSiO.sub.2 CsCO.sub.3
RbCO.sub.3 Na.sub.2 SiO.sub.3 K.sub.2 SiO.sub.3 Fe Powder (to flux)
Mn Si sample Nos. in Table
__________________________________________________________________________
1) 1 0.0005 -- -- 0.02 0.05 20 95 1.3 0.5 No. 1 2 0.0015 -- -- 0.10
-- 15 97 1.0 1.0 " 3 -- 0.09 -- 0.20 -- 25 96 0.7 1.5 " 4 0.11 --
-- 0.50 -- 20 97 3.0 0.7 " 5 0.01 -- -- 0.008 -- 16 96 2.5 1.5 " 6
-- 0.01 -- 0.013 -- 17 98 0.6 1.2 No. 2 7 -- -- 0.02 -- 0.27 7 95
1.8 0.9 No. 1 8 -- 0.05 -- 0.32 -- 8 97 2.0 0.9 " 9 -- -- 0.08 0.20
-- 4 92 1.5 0.8 " 10 0.08 -- -- -- 0.04 30 99 0.8 0.4 " 11 -- 0.09
-- 0.15 -- 18 96 0.4 1.0 " 12 -- 0.08 -- -- 0.08 16 97 3.8 0.5 " 13
-- -- 0.08 -- 0.25 15 97 2.5 0.08 " 14 -- 0.05 -- 0.08 -- 14 96 2.0
2.0 " 15 0.07 -- -- 0.16 -- 17 97 1.8 1.0 " 16 " " " " " " 96 1.7
0.8 No. 3 17 " " " " " " 95 2.0 1.1 No. 4 18 0.07 -- -- 0.06 -- 17
97 1.5 1.0 No. 5 19 " " " " " " 98 1.9 0.9 No. 6 20 " " " " " " 98
1.6 1.0 No. 7 21 " " " " " " 96 1.3 0.9 No. 8
__________________________________________________________________________
TABLE 14 ______________________________________ Usability
Characteristics, Efficiency, Fume Generation Welding Performance or
the like No. Amount (mg/min) Item Determination
______________________________________ 1 820 -- -- 2 503 -- -- 3
450 -- -- 4 400 Moisture Absorption x Resistance 5 600 Are
Stability, Spatter .DELTA.-x 6 430 -- -- 7 460 -- -- 8 840 Arc
Stability, Spatter x 9 500 Efficiency, Spatter .DELTA.-x 10 480
Strength, Pit, .DELTA.-x Blowhole 11 510 Strength, Bead Shape x 12
450 Strength, Cracking x 13 440 Bead Shape x 14 470 Toughness,
Ductility x 15 400 -- -- 16 950 -- -- 17 900 -- -- 18 370 -- -- 19
900 -- -- 20 480 Ductility x 21 450 Ductility x
______________________________________
EXAMPLE 6
This example is performed to examine the effect of reducing the
fume mainly by adjustment of the sheath metal composition and the
titania based flux composition.
Flux-cored wires (diameter: 1.2 mm) were fabricated, using steel
sheaths having the chemical compositions shown in Table 5, in which
fluxes having the compositions shown in Table 15 were filled at a
specified flux ratio. Next, each flux-cored wire was used for
performing a welding test under the following conditions.
(Welding Condition)
Polarity: DCEP (wire: plus)
Welding current: 300 A
Arc voltage: suitable voltage to obtain arc extension of 1.5 to 2.0
mm
Welding rate: 30 cm/min
Wire extension: 25 mm
Shield gas: 100% CO.sub.2 (flow rate: 25 l/min)
Test plate: JIS G3106, SM490A (thickness: 12 mm)
Welding process: downward bead-on plate welding
(Measurement for Fume)
In accordance with JIS Z 3930 "Method of Measuring Total Fume
Amount of Covered Electrode", the value per time (g/min) (average
value, repeated number: 3) was obtained by measuring the weight of
fume generated during welding for 1 min. The fume was collected by
an apparatus provided with a collecting box shown in FIG. 3.
(Usability Characteristics)
This was evaluated by sensory analysis.
From the results shown in Table 16, the following considerations
were made.
Wire Nos. 2, 3, 6, 7, 10, 11, 17, 18, 21 and 22 are cases where the
mild steel sheath compositions and the titania based flux
compositions are suitably adjusted, in which the amount of fume
generation is significantly reduced, and further the usability
characteristics (bead appearance/shape, bead sag, generation amount
of spatter, slag removability, quality in X-ray inspection) are
excellent.
On the contrary, the other wires are cases where the flux
compositions are not suitable, in which the generation amount of
fume generation is increased, and the usability characteristics are
poor.
In addition, Wires Nos. 1 to 14 are made to examine the effect of
the content of TiO.sub.2 ; Wire Nos. 5 to 8 are for the effect of
the contents of oxides of alkali metals in the flux; Wire Nos. 9 to
12 are for the effect of the Cs content and the TiO.sub.2 /Cs ratio
in the flux; Wire Nos. 14, and 16 to 19 are for the effect of the
Mn content in the flux; and Wire Nos. 20 to 23 are for the effect
of the Si content in the flux.
TABLE 15
__________________________________________________________________________
Steel Sheath Flux Composition (wt % based on total wire) Used
Alkali Metal Oxides MgO Wire (corresponding excluding Cs (metal (Mg
converted Composition to Nos. in No. TiO.sub.2 element converted
value) Cs TiO.sub.2 /Cs C Mg value) Mn Si Table 5)
__________________________________________________________________________
1 0.80 0.83 0.01 80 0.03 0.3 0.2 2.5 1.0 No. 1 2 1.10 0.70 0.005
220 0.01 -- 0.1 2.2 1.3 No. 4 3 8.30 0.03 0.04 208 0.02 0.05 0.2
3.0 0.5 No. 5 4 9.00 1.20 0.006 1500 0.004 -- -- 1.8 0.4 No. 7 5
4.30 0.007 0.01 430 0.01 0.8 -- 1.2 0.2 No. 8 6 2.40 0.012 0.002
1200 0.02 0.03 0.6 2.8 1.0 No. 1 7 7.00 1.42 0.15 47 0.007 -- --
1.8 0.4 No. 11 8 3.60 1.70 0.1 36 0.04 -- 0.4 1.6 0.7 No. 1 9 1.00
0.8 0.0004 2500 0.02 -- 0.3 2.1 0.7 No. 4 10 1.45 0.5 0.0007 2071
0.01 0.9 -- 1.5 0.7 No. 5 11 5.80 0.2 0.28 21 0.05 -- -- 3.0 0.2
No. 7 12 6.30 0.7 0.33 19 0.005 0.6 -- 2.4 1.2 No. 8 13 4.80 0.05
0.015 320 0.07 0.9 -- 2.2 0.5 No. 1 14 5.50 0.75 0.1 55 0.04 0.005
-- 1.6 0.3 No. 11 15 3.50 1.20 0.04 88 0.02 0.5 0.7 3.1 0.4 No. 1
16 3.70 0.09 0.15 25 0.05 0.3 0.1 0.4 0.7 No. 4 17 7.60 0.95 0.005
1520 0.01 -- -- 0.6 0.5 No. 5 18 2.70 0.50 0.01 270 0.02 -- 0.3 3.5
0.2 No. 7 19 6.50 1.00 0.02 325 0.03 0.1 0.2 3.7 0.8 No. 8 20 5.00
0.8 0.04 125 0.02 0.4 -- 2.0 0.08 No. 1 21 5.50 0.7 0.10 55 0.04
0.2 -- 1.5 0.13 No. 11 22 4.00 0.3 0.02 200 0.008 -- -- 2.2 1.40
No. 1 23 6.00 0.5 0.004 1500 0.01 -- -- 1.4 1.54 No. 4
__________________________________________________________________________
TABLE 16
__________________________________________________________________________
Usability Characteristics Fume Bead Spatter Quality in Generation
Wire Appearance/ Bead Generation Slag X-ray Amount No. Shape Sag
Amount Removability Inspection (mg/min)
__________________________________________________________________________
1 .DELTA.-x .DELTA.-x .DELTA. .DELTA. .smallcircle. 650 2
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.circleincircle. 550 3 .smallcircle. .circleincircle.
.circleincircle. .circleincircle. .smallcircle. 580 4 .DELTA.
.smallcircle. .DELTA. .smallcircle. .DELTA.-x 730 5 .DELTA.
.smallcircle. .DELTA.-x .smallcircle. .smallcircle. 850 6
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 650 7 .smallcircle. .smallcircle. .circleincircle.
.smallcircle. .smallcircle. 500 8 .DELTA. .DELTA. .smallcircle.
.DELTA.-x .DELTA. 880 9 .DELTA. .DELTA. .DELTA. .smallcircle.
.smallcircle. 890 10 .smallcircle. .smallcircle. .circleincircle.
.smallcircle. .smallcircle. 540 11 .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. 470 12 .DELTA. .DELTA.
.DELTA.-x .smallcircle. .DELTA.-x 910 13 .smallcircle.
.smallcircle. .DELTA.-x .DELTA. .smallcircle. 920 14 .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. 630 15
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 650 16 .DELTA. .DELTA. .smallcircle. .smallcircle.
.DELTA. 700 17 .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. 610 18 .circleincircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. 500 19 .DELTA.
.smallcircle. .DELTA. .smallcircle. .DELTA. 780 20 .DELTA. .DELTA.
.smallcircle. .smallcircle. .DELTA. 720 21 .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. 480 22
.circleincircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 520 23 .DELTA. .smallcircle. .DELTA. .smallcircle.
.DELTA. 740
__________________________________________________________________________
(Note) Evaluation of usability characteristics: .circleincircle.
(very good), .smallcircle. (good), .DELTA. (slightly poor), x
(poor)
* * * * *